DirecTV is still broadcasting in plain old vanilla MPEG2 SD on regualar DBS Ku from 101. Since DirecTV now has all their Ka bandwidth, I'm almost doubting we will see an MPEG4 transition for them in the next decade. Some local markets they have transitioned, but that is just because there is no more room on 101.
Dish, on the other hand, has generally discontinued using MPEG2 equipment for new installs. They have started free HD (which I think is the first step in simply giveing everyone HD signal and stoping the SD/HD duplication). I think Dish is simply waiting for more people to get HDTVs and get a paid upgrade. Why do it for free when people will still pay you for it? I almost expect that they will start the transition in Februrary, just after people would have goten upgrades for their new HDTVs gotten during Christmas.