And Xbox does HD DVD. But on the worldwide market, you're absolutely correct: Playstation has by far the dominant market share.
06-21-07: Fatparrot
Don't forget that Sony's Play Station 3 will play Blu-ray, so there a huge market penetration due to the sale of these machines.
Microsoft is accustomed to setting standards, but in the case of gaming, Playstation has far more market penetration.
Having recently acquired a Toshiba A2, I wonder if I bet on the wrong horse given the disparity in studio support for the two formats, but at $249, I guess I can afford to for now. If I "lose", I still have a really good upconverting DVD player and a very decent CD player, and current Blu-ray players don't do CD.
For now, Sony is sitting in the catbird seat based on movie studio support, but the high price of Blu-ray players is blunting the theoretical advantage.