it's hard to tell if the delay has to do with the game not being ready or a marketing strategy, it's not like we having seen games delayed as a marketing strategy before (SSBB and just about every game that was suppose to come out the last holiday but then was delayed due to MW).
personally, placing GT up against halo reach in the holiday period sounds like a good idea to me but it's not like any of us actually know what else sony has up their sleeve for this year, we'll have to wait for E3 first.