It'll take a while for me to edit and post this blog article, but not too long. I just got finished with an insanely busy round of giving talks; next week I'll be in Chiang Mai, but I can probably do a little blogging from there. I've always loved the idea of fluid flow as geodesic motion on an infinite-dimensional Lie group, ever since I read about it in V. Arnol'd's book, so it'll be fun to get a chance to think and talk about that!