As a matter of fact, tons of games for the 360 are in fact region free. I was shocked to hear about it myself to be quite honest. Basically, it comes down to the choice of the game producer and publisher. The console understands the regions, the publishers are usually the ones to implement them to corner markets.
This list is the most accurate I've seen. Anything that has all ticks is region free.
Of course, games that aren't released yet, such as KoFXIII, may be listed incorrectly. It's rare, but it happens. That's why I asked in case there was actual proof somewhere.