There was much confusion before the Windows Phone 7 launch as to whether data tethering would be available or not. First it was stated that it would be, then it was categorically stated that it would not. Well it looks like is actually there under the hood, and on Samsung phones there is a fairly straightforward way to enable it.
Mobility Digest has the instructions for the 2 Samsung phones – the Focus and the Optimus – and once enabled simply connecting your phone to your laptop activates USB Tethering!