Binary package hint: gajim
This bug is similar to https://bugs.launchpad.net/ubuntu/+source/gajim/+bug/340213, but that one is marked invalid... hope this one doesn't :)
The big problem is: gajim doesn't support indicator. The indicator support was introduced in 0.13.4, but unfortunately it was removed from the mercurial version due to indicator API changes (http://trac.gajim.org/ticket/5760). I've created a patch for the recent API and recent mercurial code, but they do not accept it upstream saying that maintaining Ubuntu-only code is likely to be done in Ubuntu community. It sounds sane. So I hope that it will be accepted here.