Gameloft has released several new HD games and some of them work with the Galaxy Tab, the video below gives you a preview of what they have available. You can see the Android games they have available on their Android Games page.
Unfortunately, the games are not distributed through the Android Market (based on my search) and you can only get them from Gameloft's site. In addition they are only available to certain carrier's Tab devices. If you click HERE you can see what Tab models are supported (look at your model # on the back). I have the AT&T model and I think I'm out of luck for now :(