No, that's not Windows 7 Radio Controlled or Windows 7 Royal Crown, but rather Windows 7 Release Candidate -- the ostensibly final version of the OS before it gets released to manufacturing (RTM, if you want to be as abbreviation-savvy as possible).
Microsoft's servers are sure to be swamped for at least the next day or two, but don't fret if you can't get the download right away. It'll be available until at least July (which to me says "August ship date!"), and Microsoft isn't limiting the number of product keys.
Want to know what's new in Windows 7 RC? Here's a video packed with details:
Interestingly, Windows 7 will continue to operate all the way until June 1, 2010, meaning you can give it a lengthy shakedown before deciding if you want to upgrade your office. (Note, however, that as of March 1, 2010, "your PC will begin shutting down every two hours," which strikes me as a little extreme.)
Personally, I'm not as head-over-heels about Windows 7 as many of my fellow bloggers. I like the little interface tweaks, to be sure, and the faster boot times, but I honestly can't understand all the drooling. That said, I'm downloading it right now. How about you?