Google Project Hosting just announced support for Web Hooks, which is the first time I've heard of them. Web Hooks, that is. Looks very interesting. You would think my first reaction would be "that would be so much better with Atom" since you could POST an Atom Entry, but it wasn't.
I'm not 100% in agreement with Tim, but I'm a lot closer than I was a few years ago.
The current weakness with Web Hooks is that it's just an idea, with a general description of
what to do. Personally I'd prefer a little more rigorous text around
such a thing. That might avoid the need for headers with names like