Lack of specific tranport type icons.
problem
I think the service discovery UI/dialog and related could benefit of a wider set of descriptive icons for transport types e.g., XMPP is missing, so is Twitter and so is Skype.
enhancement recommendation
Add 'em :), basically now there's just the "gajim-jabber-agent" icon for everything else and if we wanna be picky "there's no more jabber".