I just set up GAIM (2.0.0beta5, under Windows) to work with my Twitter account and thought I’d make a note of how I did it, although it was pretty straightforward.
I typed in my GMail address (the full one, i.e. with the @gmail.com part) at Twitter’s devices page and chose GTalk as the protocol. Then I added twitter@twitter.com to my buddy list in GAIM, for the GTalk (Jabber) account.
It took some time for twitter@twitter.com to come online but eventually he did, and I was able to tell him my confirmation code. He said That worked! What are you doing? Send OFF at any time to turn off notifications to this device
and that was it, apparently: now I can update my status by talking to twitter@twitter.com.
Initially I picked the wrong protocol (Jabber, since that is what GTalk is based on). Things seemed to go smoothly despite this, and apparently, based on my e-mail address, Twitter even knew I was referring to GTalk, but when I added twitter@twitter.com to my buddies list, he wouldn’t come online. The big Delete and start over
button was very handy, and after doing it the way described above, it worked ok.