The Rumor mill has started up again and it comes from Kevin Rose of Digg(we all wish we had his source). Bluray support should be built into the next update of Leopard. Apple has pretty much always backed the BluRay camp over HD-DVD, but has never revealed plans to install the players in its Macs.
The decrease of BluRay drive costs, elimination of HD-DVD as a format, and more availability will most likely result in the drives being in the next MacBooks or Mac desktop solutions. We assume that Apple is waiting for that implementation to turn on support for the high def movies. A possible announcement in October, probably not, but think MacWorld 09.