I cannot believe how much sense this makes. As app frameworks become more common, and development costs come down, I can see a point in the next two years when conference apps move from novelty to must-have. Sort of like Wi-Fi (but hopefully more reliable).
And let’s not forget the sponsorship opportunities here, either. A smart sponsor could use the app to send a hyper-targeted message to a hyper-targeted audience. Toss in some sort of booth contest, and you’ve got the marketing equivalent of the Death Star’s tractor beam.