What happens when it’s from your friends?
I have several hundred friends across the social networks I use, and even with the short updates SN’s usually enforce, these can add up. Combine that with updates internal to the SN (e.g. Bob just became friends with Sally), and I get enough information that if I were to process it all, it would really interfere with my day. However, my inability to process it all reduces and limits the value I receive from SN’s.
There are companies looking into this, including Socialmedian. If they figure it out before Facebook, Myspace, and friends do, expect Socialmedian to steal some serious thunder.