They actually do know what it is (Brett, I hope I'm not revealing too much here). Brett tested versions of this product with his old teams back at Intuit and some other organizations (including Sunfire), so people have been using it for awhile. He's been re-designing and relaunching, which is why there's so many people lined up and waiting - it's basically existing users. Well, that and people who are excited BY THE HYPE YEAAAAHAHH!

Well, having the only link on your homepage be to generate an invite probably helps.