The important thing to remember is that Sony/Blu-Ray owns Columbia Tristar and MGM, so you'll never see any of those movies out on HD-DVD. Universal is currently HD-DVD only, however they aren't owned by HD-DVD so if the market turns towards Blu-Ray they'll just support both.

Sales of media for both formats are about even now, with HD selling fewer players but more movies per player, and BD selling more players but fewer movies per player. It's hard to tell who's going to win at this point.