They are in mpeg2, Dish won't let your 6000/811/921/942 seem them though. Another ploy to force people to upgrade.
All these plans are so silly. Its obvious their mpeg4 encoders aren't ready for primetime. Its also obvious they don't have enough 211/622s to cover the demand for upgrading everyone and new customers. So why not just allow existing HD owners access to the channels in mpeg2 while they get their crap together?
New customers would get the new boxes for the time being (even though nothing is in mpeg4 yet). Existing subs would get a taste of the new content while its in mpeg2. There would have to be public service announcements on those channels stating "This is just a preview, On xxx day, they will require a new box."
Assuming it takes several months for them to iron out their mpeg4 problems, they might have more inventory of 211/222/622s to allow existing customers to upgrade their whole system.