Phone
SMS
Email
Calendar
Google Talk
Y! Messenger
Facebook
Twitter for Blackberry
It can also do BBM, the rest of the IM programs (AIM/MSN), other Social Networking sites (MySpace, etc), Tasks, Coverage Indicators, Battery Charging/Full/Low, and other 3rd party apps (weather, viigo, etc).
In short, it can do what you're asking it to do. I'm not 100% on Ubertwitter but I believe BerryBuzz 3.0 will allow it.