The Assassin's Creed conference demo was rushed because Bungie couldn't get a single-player Halo 3 demo ready in time, CVG hears.
Apparently the reason Jade Raymond and her accomplice had a few issues with the live playable demo (that was a bit buggy in places) was that the Montreal development studio had to rush to get something ready for the show as the request of Microsoft. This apparently happened because Bungie couldn't get a playable demo of Halo 3's single-player campaign ready to show in time.