i guess you like long pauses while you browse the internet, cuz the internet on my iphone is pretty slow. not unusable though.I hit a GB the other day, but then I restored my phone to test iFuntastic 3 which was a waste of time so I can't tell you the exact amount.
I got my phone on release day, restored onces after two weeks, so that was like what? A month and a half of use?
I think it depends on whether you add your restored iPhone as a new one, or use an old profile saved in iTunes. In the latter case, I know this restores the SMS/call logs/misc. prefs... and might include your usage stats. Can someone verify this? I don't plan on restoring any time soon...like i said, one time it cleared my stats, and one time it didn't. i don't think it's supposed to though