It's strange that we have to wait 21 days for the Halo 2 trailer, but Smilebit thinks he knows why. He writes in the HBO forum:

The Halo trailer is encoded using WMP9. The Windows Media Player 9 beta comes out on Sept. 4th.

So IS Windows Media Player 9 coming out September 4? You betcha. My main concern is, will a Mac version be released by that time?