Wow, although most Blu Ray releases are now MPEG-4, I have found that Shooter [which is just about to be released] is encoded in MPEG-2 on Blu Ray. And oddly it's encoded to MPEG-4 on HD DVD. Weird because I thought when companies did dual format releases, they used the same codec for both. But I guess I was wrong.
Here's some comments about it from the high def digest review:
Paramount brings 'Shooter' to both HD DVD and Blu-ray about a month after the standard-def DVD, and (as is commonplace today with new releases), all are minted from the same high-def master. The HD DVD edition receives an 1080p/AVC MPEG-4 encode, while its Blu-ray counterpart gets the MPEG-2 treatment. Both transfers looked identical to me.