I ran it once on WiFi and once on MSP 3G.
Houshold DSL speed: 5.5 mbps down, .75 mbps upiPhone WiFi: 5.8 mpbs down, 0.71 mpbs upiPhone 3G: 2 mpbs down, 0.08 mpbs up
The iPhone WiFi performance was limited by our home DSL speeds.
The 3G download performance was pretty good. The 3G upload performance, however, was really bad. It's comparable to a modem. AT&T's 3G upload is 4% of download performance. No wonder posting images to Facebook, or to Evernote, is so slow.