I am not 100% sure (Scott, Longhorn or Robert should be able to add better info) I have read that the HD receiver would be released around the 1st quarter of 2006 and it SHOULD be interactive, but it will be an upgrade (along with the new dish) on a per market basis and available for retail purchase otherwise.
The DirecTV branded DVR was rumored to be a bit later (maybe 2nd qtr) but I have read nothing about its feature set and the DirecTV Home Media Center, even later; but no one knows for sure because DirecTV was thrown a HUGE wrench by not having the launch schedule work out, so they are many months behind.
This info is based on things I have read and tried to piece together the facts, but I am sure this post will get a lot of replies for you, so keep your eye on it.