Google is blocking Android Market movie rentals on rooted devices because of copy protectionhttp://www.engadget.com/2011/05/21/goog ... d-devices/
Rooting your Motorola Xoom won't stop you from getting an LTE hardware upgrade, but it will throw up a roadblock if you're trying to watch movies rented from YouTube / Android Market. Android Central points out a Google support document that details the "Failed to fetch license for [movie title] (error 49)" message users will see when they try to play a movie on a rooted Android device. Only Xooms with Android 3.1 have access to the service right now, but once support rolls out to all Android 2.2 or higher devices in a couple of weeks some will have to choose between their superuser privileges and Google's nascent movie offerings (at least until someone figures out a workaround anyway). So far rooting and jailbreaking hasn't put a stop to other movie rental services for mobiles (iTunes, Netflix) so even if Google blames the movie studios for the policy, it seems like an odd restriction for the company behind the "open" platform to have.
In the near future, having a rooted device might cause you from not being able to watch Netflix movies. I'm not sure what kind of root it will detect, so it might still be safe to do roots that don't give R/W on the /system partition. Not sure yet though, we'll have to wait and see.
When this hits, I'll definitely check it out... As it should block me, because I'm rooted on every device I have.