At the suggestion of a friend, I’ve moved the source code for the Stratoballoon from my SkyDrive to GitHub: https://github.com/markegilbert/Stratoballoon. This should make it easier to get at, and you’ll be able to see the evolution of the sketch going forward. We’re releasing the code under the MIT License (https://github.com/markegilbert/Stratoballoon/blob/master/LICENSE).
As a quick update on the project itself, Katherine and I were able to get the GPS receiver working. We’re still in the process of incorporating the code into the master sketch, but we should have that wrapped up this week.