Yesterday's news that Microsoft had acquired Parlano wasn't all that unexpected. If anything, Microsoft is a little late to the game adding persistent group chat to Office Communications Server. It's been a hot feature of consumer IM / VoIP client Skype for some time now, variations continue to show up in tools like Twitter, and those of us with grey hair also remember the popularity of IRC.
By adding persistence to it's enterprise products, however, Microsoft gives enterprise managers the comfort of being able to manage these persistent chat sessions. In the financial services market, where Parlano has had much success, this is an absolute must have. In government, public relations, or sales these same features would also be welcome. Imagine, for instance, a live FAQ — log into the persistent chat session, ask a question, get an answer… and leave that answer for the next person who needs it.
Additional reading: Burton Group's Mike Gotta has some in-depth coverage.