Gwibber was an interesting problem user-interface wise as, although there are many Twitter applications with great UIs out there, there aren't many that have to:
1. Support multiple accounts from different services, presenting the information in one stream to the user
2. Be able to filter the main view to one account (i.e. choosing to only see Twitter-related material in the views)
3. Integrate into many different desktops, but still try and have it's own identity
So, after thinking about these points and also looking at/using the best microblogging applications on Windows and Mac (Seesmic, Tweetie, TweetDeck), I've stolen a lot of ideas and come up with:
Theme-wise, they are obviously using Ubuntu's Ambiance theme as the palate, but I think the look would work fine on Fedora/SuSe as long as your taking the right colours from the Gtk theme. There is controlled use of gradients to work better with Gtk themeing (so you get something good looking without having to write tons of custom widgets which do lot's of drawing). There is use of some DX-team tech (Windicators, CSD), but nothing that couldn't have a simple fallback on other desktops.
I have highlighted some of my favourite things in the next image:
Okay, time to pack bags for flight tomorrow to Prague for the Platform Sprint. I've got more ideas for other applications that could fit into this style (Rhythmbox and Evolution are on my radar), if you guys like it.