Google told ZDNet that it isn’t officially blocking tethering apps. However, Google does say that Android users on specific carriers may not be able to find the app in the Android Marketplace. In other words, Google isn’t denying that certain apps are being blocked by the carriers.
One of the great aspects of being “open”. Now, it is true that Android is open, but the ones reaping the benefits of this openness are mostly the carriers. The end users? Not so much.