For me, the main reason why sony or microsoft can't just copy the revo controller is that any new controller they release will be deemed an "accessory" to the base console rather than the primary controller. As we have seen in the past games that use specific accessories (eye toy, bongos etc) aren't as prevalent as the games that just use the default controller because developers don't want to reduce their potential audience to those that have the accessory. Where revolution succeeds is by having the "accessory" as the default controller, leading to no decrease in the potential audience so the developer is free to use the features of the controller to the full in all games.
It will be interesting to see the direction sony and microsoft take with their next consoles in 5-6 years time, i guess the direction will depend on what the public make of the latest batch of consoles. If the revo really takes off, i imagine the next ps controller will look pretty much the same as it always has, but will have an integrated motion sensor like the current revo controller.