Some people have reported they are able to tether (via USB only) with the EVO on 2.1 and 2.2, so I dont think Froyo has anything to do with it. However, I cannot and most of the people of that particular thread report they cannot either. So I would say the answer is no. But, you can download an app from the market called PDANet (and there is another one, cant remember off hand) and it will allow you to USB tether for free. I have used PDANet and it works well.