I'm still not exactly sure what Userplane does, but I know every page that MySpace loads seems to call a userplane server. Seems to be a pretty integral part of the system, which makes AOL's acquisition really interesting.
I hope their social networking know-how can provide a nice boost to AIMpages. I remember back when doing your AOL profile was the 1998 version of MySpace and still feel like anything powered by AIM has the potential to be a great social network. Adding folks who have been doing it for five years can only be a good thing for Team Yellow Guy.