Is WebRTC implemented in any browsers yet? Nightly builds?
Thanks for any info.
It's now implemented in Chrome 18 (dev track and canary).
Some support has landed in WebKit recently, and Mozilla is also actively working on both the spec (IETF and W3C) and incorporating it into Firefox.
FYI, I work on this project for Mozilla.
Note: This answer is outdated, see answers below for current information.
Do you accept "No" as an answer? It seems to be a project in early stages and their blog has only a few entries - if any browser vendor adopted their solution I would expect to see a big announcement there. So far they only have a blog post titled "First Step Toward Chrome Integration" which seems to indicate that some prerequisites landed in Chrome but not the actual WebRTC support yet.