HDTV Audio Formats

[picopir8]

I know HD supports Dolby Digital, but what about DTS, DTS ES, and Dolby Digital EX?  Are those supported in the standard?  As long as broadcasters are buying new hardware to provide 5.1, why not go directly to one of the 6.1 or 7.1 formats?  Unless, of course, the 6.1 and 7.1 formats are not supported in the broadcasting standards.  Granted, DVDs utilizing the newer formats are beginning to pop up, but until HD DVD comes out, it looks like you will have better sound or better picture but not both.  Granted the better picture of HD far outweighs 1-2 extra channels that the new sound formats add so its a no brainer, but it sure would be nice to have the best of both worlds.