I expect this means the ABC regional games will be HD on Gameplan but I've seen nothing to indicate the ESPN+ or any of the locally produced games will be HD.
This is the big qualifier. D* or ESPN can't "force" a local/regional broadcaster to convert to HD, so the broadcast through Game Plan is really only as good as the source material. We know CBS is HD, NBC/Notre Dame is HD, FSN has a lot of HD, and ESPN is HD (or close to 100% anyway). But groups like Raycom/LincolnFinancial (RLF) is not always HD. RLF is moving towards HD, but I would be very surprised if every regional game from RLF was in HD this season. Considering they only did a couple HD basketball games this past season, and I don't recall seeing any HD football, they would have had to do a bunch of hardware/equipment upgrades this summer to meet the demand for 100% HD. They are moving that direction, for sure, but don't hold your breath.
And IIRC, one of the main stumbling blocks for outfits like RLF is that they are a syndicated provider and the local broadcasters that buy into RLF have different standards or receiving/retransmitting HD (720p/1080i).