About the only things we know for sure about 2.0 are that it will be a free update for everyone, and it will include native email (actually native PIM, so more than just email).
There are only a couple of other things known (video store, some enterprise stuff), and lots more speculated about and ranging from unlikely to expected.
Just wanted to rebut the "RIM has not told us yet", since this has been quite clear.
It isn't just based on what RIM has or hasn't said. In certain preview versions you can go into device settings and there is a new "Accounts" tab, where you can enter information for e-mail and Facebook accounts.
This was in the last virtual machine simulator I downloaded, and I entered one of my accounts. The vm did NOT have the actual e-mail program (deliberately held back), but I was able to successfully log in to a POP3 account and have the device give me a push notification (and even a preview from the icon on the upper left).