Hmmm. More activity from Facebook. This may be an assault on Twitter – but Twitter didn't work because is was simple. It worked because of Tweetdeck, or Twhirl, or Twitter Search – i.e. because you could use and access Twitter in many ways from many places. Facebook has always had a twitterlike function in terms of its status updates (they did this well before Twitter was around). But because these were contained within the Facebook walled garden, they didn't 'become' Twitter.