A few months ago AOL found a way to fuse AIM, its popular instant messenger client, with the broader messaging systems like Facebook and Twitter that have begun increasingly important on the web. AIM now includes a new tab dedicated to the lifestream - a combination of your friends' activities on Facebook, Twitter, Flickr, AIM itself, and a variety of other services (think of it as a FriendFeed with integrated chat). Tonight they're bringing the lifestream to the iPhone with AIM 4.0, which is now live on the App Store for $2.99 (the free version doesn't currently offer this functionality).
The new iPhone app will let you monitor updates from all the services supported by the desktop version of Lifestream. The app also lets you simultaneously post your AIM status updates to Twitter and Facebook - while the Lifestream was read-only until recently (you couldn't post messages to services other than AIM), the service recently enabled this functionality.
Other new additions to the app include photo uploading, photo viewing on the Lifestream, and various UI improvements.