Just to clarify. Disney did a test using the Nintendo Ds as a base (you had to have Disney's software on their own DS') It had park info, maps and the like. From what I heard people did enjoy it, sounded pretty cool. I would like to add that it was not people's personal DS' that were used. Guests had to put down a $300 deposit to participate in the pilot, so they could use Disney's own equipment. Disney had uploaded special software onto the device. It was a trial run. Please do not expect WDW to let you use your own DS' in the park for that kind of service at this time. Seriously, where's the profit? I can only see that working if you did it wifi, pay for view.
Still sounds pretty neat though. Let's hope something affordable crops up out of this testing.