This may well be the coolest thing that I've ever seen as far as mobile apps are concerned: an interactive map of the Orlando convention center (yes, where I will be next week at TechEd!) that uses the camera of your Windows Mobile phone. Basically you use it to take a picture of one of the "signposts" that they will have up all over, and it shows you where you are and what sessions are going on near you. Check it out:
If they integrate it in with individual attendees' schedules (so I can see not just what sessions are going on, but which of the sessions I've added to my schedule are going on) I might lose it because it's too damned cool.