Massively by joystiq just posted 500 new invites to beta, if you have buddies that still need to get in on this before it goes live, I suggest you send them over there quickly!

I just got 2 of my friends to sign up.

http://massively.joystiq.com/2011/03/21/preview-spiral-knights-with-an-e...

In fact it seems if you do a google search you can find news stories pretty frequently giving some links to sign up to get in on the action. Seems like the servers are going to get more and more crowded as release approaches :)