Which is not very practical when you have multiple channels open...
Upstream bug is http://bugzilla.gnome.org/show_bug.cgi?id=535042
This very well could be due to a problem with telepathy-idle since jabber chatrooms titles are set correctly.
Yes, it is telepathy-idle issue, filed as http://bugs.freedesktop.org/show_bug.cgi?id=16345
This bug appears to have been reported against 'rawhide' during the Fedora 10 development cycle.
Changing version to '10'.
More information and reason for this action is here:
This has been fixed in the most recent version in Rawhide.