On twitter, I'm starting to think of it much less as a social medium and much more as a real-time news channel.
When the quake hit NZ I found out on twitter a full hour before the BBC News channel announced 'breaking news'... Moreover, the best way brands have found to use it to date is through time-sensitive promotions, and news about offers.
Equally, consumers seem to be using it for communicating news back to brands about their experiences with their product or service, good or bad.
Of course mostly it's used as self promotion so it feels like twitter is turning into just a set of 'news headlines' - 'a bulletin board for brands' - (whether a corporate brand or your own personal brand) rather than a truly space for groups of people to discuss. In other words a two way news channel which inevitably becomes a sales channel. Interesting.