Just tried Gaim2 beta3. Apart from the fact that I had to use GTK2.6 (GTK2.8 bug in GIOChannel) I was happy to see they *somehow* cleaned up the UI. IMO Chat window stills looks like 1998, and the avatar of the person you talk to, in the top left really sucks as design.
But the good stuff are stuff like mouse over activity in gtktextview for links (aka. hover), smooth scrolling and better organized places for settings and plugins and plugin settings. Also account management, signing in etc seem 2006 instead of 1998 (Gaim1.5)
I hope GTK 2.8 stuff is fixed soon on GTK, so they can take advantage of GTK 2.8 only stuff (like the urgency hint, which you can enable via the GaimWindows Only Plugin only for Windows..). In fact even GTK 2.10 when is out, would provide so much more out of the box (f.e. trayicon [with let's hope] popdown of menu automatically on "focus-out").
Iif you are a Gaim1.5 user, go 2beta3.
PS. one idea I liked but is done P O O R E L Y in terms of good looking UI, is the connection error as button. At least I hope in GNOME that looks better, though I doubt it would look more nicer. F.e. this should be done as sticky ballon type tooltip on the trayicon. OTOH, I'm not sure if ever in Linux we could see such a tooltip (without the need of notification-daemon) [or at least, a happy trayicon API to add such "user must see, and can click for more info" tooltips"]