Patrick Leyden at InsideMacGames has posted a final wrap-up of E3, with Myth III figuring quite prominently:

Many were skeptical about a new Myth title coming from someone other than Bungie, but after experiencing the game for only a short time I can say without reservation that such skepticism is unnecessary. Myth III is an absolutely stunning game, with its fully 3D characters, enhanced environmental and lighting effects and a combination of new as well as classic units to send into combat.

The article also mentions other upcoming games on the Macintosh platform. If you're waiting for the Macintosh version of Halo, it might be worth taking a look to see what you'll have to occupy your time while you wait.