Not in the UK any more, at any rate:
http://www.inquisitr.com/?p=2390 Update Edit (18/08/2008): Possible forthcoming alternatives...
http://www.inquisitr.com/?p=2462 And the current state of Twit-related play...
http://www.businessweek.com/technology/content/aug2008/tc20080815_597307.htm