Sorry for not addressing that first time-round. We are funded by the Google and Gates Foundation grants plus private donations. As far as "most", I am not totally sure. I have very gladly stopped worrying about the particulars there as we've got some great folks (Sal, Shantanu, and Jessica) focused on making sure we're funded well enough to keep making progress at the rate we want. That frees up me and the rest of the developers to focus on building the product. Charmed life, eh?