No, no black bars. The 360 is at a friends house and I will be going there this evening. I am almost positive I had the 1920x1200 option, but I may be wrong...errr....come to think of it, maybe I was just mistaking that res for 1080P, which of course IS 1920x1080
None the less let me check it this evening and I will post back in this thread.
1920x1080 is currently the highest resolution supported by the 360. I doubt that you'll see anything higher in the lifetime of the console.