Augustine: windows mobile device can provide WiFi (internet connection sharing) over 3G for the iPhone/iPod Touch
from Gizmodo by
Jason Chen 
After tooling around with getting internet sharing working on the Sprint Mogul for a bit, we discovered this small WMWifiRouter app by Jorrit Jongma. It's pretty much an install and run affair (save a bit of internet connection Wi-fi setup beforehand), but the only thing you have to watch out for is using a static IP address on the device you want to access it with (iPhone/laptop/whatever) because there's no DHCP server present. There's a good guide in the XDA Dev forum as well. The result? A 3G-ish iPhone. [WMWifiRouter]