I don't know about you, but all the free/cheap online content streaming I have found has some form of adversting such as: Hulu/Dish, Crackle, occasional Netflix, etc.
They are all the same, you will never get rid of the commericals completely, especially with Roku or other devices like PS3/Xbox. Even illegal content has commericals. As others have mentioned, Internet Caps are just in their infancy. Otherwise, I would of ditch Dish/Directv along time ago because of this. That and it's not logistically feasible to recieve OTA at my location.
We don't get any commercials on Roku except for the 30 second Hulu bits.