Connect to AT&T's 3G network? ZING!!!

Haha, all kidding aside, to be honest, until the first full reviews of the N900 come out, I think it's going to be a bit difficult to see.

The main difference that Symbian holds (against other smartphone OS', too) is that it's a phone first, mobile computer second. That's why it works so good for normobs who ease themselves into it.

Maemo, on the other hand, is quite clearly a mobile computer first, phone second.

While that might seem obvious, it's a very important distinction, and Symbian users coming over to Maemo will, in some cases, have to completely alter their usage to fit Maemo.