Since yesterday we’ve returned to an open signup system, where any user can sign-up immediately. We had to temporarily place limits on new user signups while we experienced very high demand, but we’ve added additional resources that should keep us going strong for a while.
We’ve also completely emptied the invitation queue — if you haven’t received an invitation by email (we had about 3% email failure rate: bouncing, etc), you should be able to sign up for an account immediately.
Thanks again for your patience while we grow, and for your feedback. We’re aware of a couple bugs, and have some great features planned for release this next week.