Comment 7 for bug 306469

Looking through the code, this really looks fixed if not in Karmic, then definitely in Lucid and later releases. That's what the "no-auto-default=<mac address>," key in /etc/NetworkManager/nm-system-settings.conf is for, and is automatically added when Auto eth0 is created so that it doesn't get re-added if deleted.

Since we're talking wildly different code between 0.7 and 0.8, please open a new bug using ubuntu-bug (and tell us the number here) if you see that it is still broken in Karmic or Lucid.