The latest word from LFL is that there won't be any more video releases until its on HD, and they aren't going with HD until the format war is over. Since it seems that Blu-Ray has now won the format war--or, to put it more fairly, that by the mid-year HD-DVD will probably be obsolete considering where things are now--LFL might start organising the HD set sometime this fall. That could mean that we could see the set as early as christmas 2009--since I think a lot of the extra content will simply be the pre-existing DVD extras, and even though there has been talk about an "all bluescreen" version of TPM or OT deleted scenes or more extensive PT docs this could easily be put together in under a year since theres no need for commentary tracks, OT interviews, etc. Given Lucasfilm's track record though I can easily see it taking until 2010, which would put it in sync with the live-action series.

AOTC and ROTS were shot in standard HD res, which is 1080p. But then they are cropped so I guess you are right in that they are less than the full res of HD.