Not sure how widespread this is, but at least two of the new HD channels that Comcast recently added in my area (98027):
665: FX HD
653: Lifetime HD
have program information that is 3 hours off. This has been true for several days, because my season pass for Damages on FX HD recorded Wed at 7pm instead of 10pm. Grrrr.
This could be a Comcast issue, because I spot-checked a number of the other new HD channels (Bravo HD, IFC HD, TBS HD, ...) and they match their guides. The HD shows on those channels are listed 3 hours earlier than their SD counterparts, but that's OK, because the HD feeds have been time-shifted to match the guide.
So, either Comcast is supposed to be time-shifting the FX and Lifetime HD signals downward, or the program guide provider (Tribune) is supposed to be shifting its guide info upward.
: IFC is a little different. IFC (503) and IFC HD (699) show the same content at the same time, and their guides are identical. This makes sense, because the SD version of IFC is simply named IFC, whereas the SD versions of Bravo, TBS, Lifetime, and FX are named BRAVOP, TBSP, LIFEP, and FXP.
Assuming that P implies Pacific and non-P implies Eastern, and assuming the HD channel labels are accurate, then the problem with FX HD and Lifetime HD is guide-related and therefore TiVo/Tribune's problem, not Comcast's.