Rated 5 out of 5 stars
Works with thunderbird-5.0-1.fc15 (when install.rdf is fixed as seen in https://gitorious.org/bugmail/bugmail).
Rated 4 out of 5 stars
It runs XML-RPC to find out current state of the bug, right? Would it be possible to add some functions to actually change the bug as well? (add comment, change needinfo, change state of the bug). I am willing to help with support for bugzilla.redhat.com