Looking at the log file that Matt R referenced above, I did some digging around and there's a traceback in there around not being able to set the network info cache:

2013-11-21 23:15:52.403 ERROR nova.network.api [req-b2745c05-f148-4a09-aa34-ffa8d7d9d1cd demo demo] [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95] Failed storing info cache
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95] Traceback (most recent call last):
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/network/api.py", line 74, in update_instance_cache_with_nw_info
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     nw_info = api._get_instance_nw_info(context, instance)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/network/api.py", line 49, in wrapper
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     res = f(self, context, *args, **kwargs)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/network/neutronv2/api.py", line 456, in _get_instance_nw_info
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     nw_info = self._build_network_info_model(context, instance, networks)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/network/neutronv2/api.py", line 984, in _build_network_info_model
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     context, instance['uuid'])['info_cache']['network_info']
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/conductor/api.py", line 74, in instance_get_by_uuid
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     columns_to_join)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/conductor/rpcapi.py", line 165, in instance_get_by_uuid
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     return cctxt.call(context, 'instance_get_by_uuid', **kwargs)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/rpcclient.py", line 85, in call
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     return self._invoke(self.proxy.call, ctxt, method, **kwargs)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/rpcclient.py", line 63, in _invoke
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     return cast_or_call(ctxt, msg, **self.kwargs)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/openstack/common/rpc/proxy.py", line 126, in call
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     result = rpc.call(context, real_topic, msg, timeout)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/openstack/common/rpc/__init__.py", line 139, in call
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     return _get_impl().call(CONF, context, topic, msg, timeout)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/openstack/common/rpc/impl_kombu.py", line 816, in call
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     rpc_amqp.get_connection_pool(conf, Connection))
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/openstack/common/rpc/amqp.py", line 572, in call
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     rv = multicall(conf, context, topic, msg, timeout, connection_pool)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/openstack/common/rpc/amqp.py", line 566, in multicall
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     conn.topic_send(topic, rpc_common.serialize_msg(msg), timeout)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/openstack/common/rpc/impl_kombu.py", line 720, in topic_send
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     self.publisher_send(TopicPublisher, topic, msg, timeout)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/openstack/common/rpc/impl_kombu.py", line 691, in publisher_send
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     self.ensure(_error_callback, _publish)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/openstack/common/rpc/impl_kombu.py", line 577, in ensure
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     return method(*args, **kwargs)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/openstack/common/rpc/impl_kombu.py", line 688, in _publish
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     publisher = cls(self.conf, self.channel, topic, **kwargs)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/openstack/common/rpc/impl_kombu.py", line 369, in __init__
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     **options)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/openstack/common/rpc/impl_kombu.py", line 316, in __init__
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     self.reconnect(channel)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/opt/stack/new/nova/nova/openstack/common/rpc/impl_kombu.py", line 324, in reconnect
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     routing_key=self.routing_key)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/usr/local/lib/python2.7/dist-packages/kombu/messaging.py", line 82, in __init__
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     self.revive(self._channel)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/usr/local/lib/python2.7/dist-packages/kombu/messaging.py", line 216, in revive
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     self.declare()
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/usr/local/lib/python2.7/dist-packages/kombu/messaging.py", line 102, in declare
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     self.exchange.declare()
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/usr/local/lib/python2.7/dist-packages/kombu/entity.py", line 166, in declare
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     nowait=nowait, passive=passive,
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/usr/local/lib/python2.7/dist-packages/amqp/channel.py", line 612, in exchange_declare
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     (40, 11),  # Channel.exchange_declare_ok
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/usr/local/lib/python2.7/dist-packages/amqp/abstract_channel.py", line 73, in wait
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     self.channel_id, allowed_methods)
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/usr/local/lib/python2.7/dist-packages/amqp/connection.py", line 220, in _wait_method
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     self.method_reader.read_method()
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]   File "/usr/local/lib/python2.7/dist-packages/amqp/method_framing.py", line 195, in read_method
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95]     raise m
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95] RuntimeError: maximum recursion depth exceeded while calling a Python object
2013-11-21 23:15:52.403 4036 TRACE nova.network.api [instance: d3bd703c-a3f4-4e83-8ab0-a2f3e603ec95] 

The traceback indicates that perhaps there is a recursion limit in the amqp method_framing.read_method function?