Facebook has a post that explains how you can now send updates to Twitter using Facebook. This could be useful for people who maintain both a Facebook account and a Twitter account. Mashable writes that Facebook is probably hoping the ability to tweet from Facebook will make people want to use Facebook first.
While that makes a lot of sense from a convenience standpoint – many big time Twitter users also have popular Facebook Pages and vice versa – it's surprising to see Facebook so openly acknowledge Twitter's reach. That said, by giving users the ability to update both services via Facebook, they're clearly hoping that the Facebook Page will become the first stop for admins.
That would mean lots of "via Facebook" messages showing up in tweets, and in fact, it’s not hard to imagine Facebook quickly becoming one of Twitter's most popular clients. However, I wouldn't expect this functionality to be extended to user profiles anytime soon, which would clearly be a bigger win for Twitter than Facebook.
There were Facebook apps that let you do this before but now Facebook has made it easier with this new Twitter app. It could lead to a big increase in the number of updates appearing on Twitter. It could also get confusing for users as people respond to an update from Facebook on Twitter. Unless those responses on Twitter also come back to Facebook then Facebook users are still going to have to come over to Twitter to see them.
Facebook has a 
