There's a workaround for tethering for a few handsets, just not all of them. There will most likely be more workarounds in the future for the newer handsets with the better wifi chipsets.
Also, do any of the carriers allow tethering without a plan? Sure you can get away with it a little bit, I am sure that if I had ever been in a bind I would have jailbroken my old iphone, installed PDAnet and then tethered it to my laptop. Hypothetically of course. But strictly speaking, don't all major US carriers (read: the ones that carry WinMoPho) require a plan?
