It turns out the battle for control of Twitter rests almost exclusively in the unique value proposition of XMPP-served track. As Twitter strips away various features of its service to rebuild a scalable fail-whale -proof version, the one remaining hurdle is restoration of a fully-functional Track over IM.
For the last two weeks, a one-way IM service via Gchat inside Gmail or Gtalk standalone has provided a stream of tweets but not the previously enabled ability to post back to Twitter via the IM window. In addition, there is no support for the Track function, which interweaves Tweets from any endpoint on the Twitter network that correspond to the keywords you “track” on. Track was briefly available over SMS several weeks ago, but was then withdrawn.