This is really strange because when I was on 2.2.1 the edge connectivity was horrible. I had to call at&t and apple support to find out why and they recommended resetting my network settings. That worked maybe 1 out of 5 times.
Now with 3.0, I'm constantly connecting to edge. The speed seems normal for edge but its usable. I think this has to do with the phone constantly trying to connect to the internet (which is causing battery drain and warm phones) so its always trying to re-establish an edge connection. Or maybe they just improved the software.
It could also depend on what region your in.