I am teathering through my Mogul right now as I post this. I'm on Windows XP SP2 using USB. All I had to do was go to the Internet Sharing application and select Sprint PCS as the Network Connection. It made me reboot the machine as it must've installed a driver, but once I got up it worked. I did notice it say a couple of times that I had an invalid username/password, but they may have just been a fluke.

As a test I am getting a steady 70KB/s downloading on EVDO with 3 bars.