Just to clarify:
Uru: Ages Beyond Myst is 2 games. One, Uru, is a single player experience, no online required. Doesn't even require you to use the enclosed CD-Key.
The second, Uru Live, is a MMO game, with a primarily exploration / social focus. Uru Live is what has been delayed. It DOES require the CD-Key to create a unique account, which at some future time will be a billed service, though from their own descriptions that won't be until sometime early next year. THIS is what has been delayed. The game shipped to stores on time, the single player works exactly as described, but you can't access the massively multiplayer section of the game yet.
Hope this helps