Here’s a good rule of thumb: “Don’t update your firmware five minutes before you’re going to fly an autonomous robot ten feet away from a former Vice President of the United States.”
That was one of the afterthoughts of [Chris Anderson] after presenting his Arduino controlled blimp at TED. (I might have to squeeze TED into my con schedule next year.) The project itself is somewhat documented here, with some hi-res photos, parts list, and some firmware. Apparently the blimp was overcome by the A/C in the auditorium, but I still dig it.