Don't be counting your 3Gs before they hatch, there are no plans just yet.
There will even be WiFi before 3G, but WiFi only available... where it is available.
Your best choices are EVDO (fastest) on Sprint and Verizon [8830] or EDGE on AT&T [8800, 8300, 8700] and TMo [8800 or 8700].
Yes, a newer model 8800 or 8300 on AT&T's EDGE network, will be faster than you current 7130. I think I said that in the first post?