Answer by jhagedon · Jul 23, 2010 at 10:33 AM
Seesmic for iPhone does Twitter, Facebook, and Ping.fm. Better yet, Google Buzz or Buzzie for iPhone can be set up to also post on Twitter and Facebook. Just post once on Buzz and it auto-posts to the other services. Posterous is very good also. it works with almost everything. You can send updates via email and it auto-posts to everything you want it to. There is no dedicated app, just use any email provider.