Beta started late in the year last year, but it didn't really kick off till around the end of January when we made our first big updated to the client and started bringing in more players.  I've lost count in regards to how many people have invites to the beta now, but it's well over 100k by now.

For the most part we've maintained a schedule of weekly updates, which has been great for turn-around on feedback and bugs.  It's a busy schedule to maintain though, because the PC beta is not the only product in development for this game, which means we need to develop all of the platforms at the same time.  

I've recently spent a bunch of time working on the tuning of the PS3 Move/Sharpshooter controller, which has been a really interesting experience.

Anyways, beta is trucking along, the game is looking really good, and I hope some of you have gotten a beta key to enjoy it.  If you haven't signed up for the beta survey you should go to http://blog.counter-strike.net/ and sign up.