Why do we need Twitter and Facebook?  (esp. after Facebook’s redesign, making it much more Twitter-like)

One reason:  tweets are 100% public, Facebook status updates are (generally) not.

As such, the collective tweet-stream is a great source of near-real-time information.  Lately, I find myself searching more than tweeting, mostly to find current info or if others are sharing my current problem (e.g. “EC2 down”).  When I do tweet, I’m tweeting more to a search result audience (e.g. “lots of spam getting throug gmail”) than to my immediate friends.  But I’m not sure this is typical behavior.

Twitter really wants to be a feature on Facebook.  I think they (Facebook) could pull this off if they came up with a manageable way to deal with privacy scopes:  100% public, semi-private, etc.