got it working finally
i had an issue, but just got it sorted out. i could use EDGE, but not wifi at my house. i have a Belkin router, and the network was working fine for everything else, with WPA security turned on, firewall turned off.
here's what solved it, in case it helps anyone else:
Under settings>wifi, the iPhone has a space for the DNS server. Mine was filled in with three addresses - the router and two others. (the router is set to auto-detect the DNS server). I deleted the router's address and left the other two, and everything started working properly.
good luck!