On Apple TV 2 you cannot buy Movies, you can only rent them, even in the USA. What has been added, and was available only in the USA up until now, is the ability to purchase TV shows directly from the Apple TV 2. In the USA, prior to 'iTunes in the Cloud,' when you purchased TV shows on Apple TV 2 they would automatically download to your computer as well if you had a computer iTunes account also set up. There was a setting in iTunes preferences to do this called 'Always check for available downloads.' If you did not have a computer with iTunes set up to download automatically you would no longer have access to those shows since an Apple TV 2, as we know, does not have sufficient internal storage to hold any content. Although it was a shortcoming of the system it was also an unlikely scenario as anyone with an Apple TV would likely also own at least one computer. 'iTunes in the Cloud' solves the problem of accessing this previously purchased content regardless.
Some history! When Apple TV 2 was first introduced Apple also introduced TV show rentals in the USA. When that did not catch on they changed Apple TV 2 so that you could purchase TV Shows instead. That was exclusive to the USA market and Apple TV 2 everywhere else went without the Television menu until now. In markets where the Television menu did not exist, TV shows could only be purchased from a computer and then streamed locally over the LAN.