We've forked the Blimp UAV into two projects, a minimum and a maximum one. The maximum one is the one that's using the NorthStar "synthetic GPS" directional system and all sorts of other goodies to be a real indoor UAV, with full room sense and navigation ability. That's moving ahead really well, and I hope to have PCBs and code to show you soon. But we also wanted to create a "minimum" blimp UAV that was the cheapest, simplest robotic blimp possible.
All that this Blimp UAV is designed to do is to maintain a constant altitude and navigate around a stationary IR beacon on the ground (it just heads towards the beacon, overshoots, turns around and heads back at it). But that's the beginnings of real autonomy!
Target price: <$100 (we're not there yet).
Here's a video that shows how the Pololu IR transceivers work (and here's some BS2 code to test them):