The requirements for registration are just email, username and password - no more or less than would be asked if you signed up for Twitter or Flickr for example.

We've been working on the website since it became publicly accessible last Wednesday and continue to evolve it as we get feedback. The team (3 people) comes out of research not website development so we're rapidly moving up the learning curve on implementing all the finer points and details. We didn't want the great to be the enemy of the good (enough) to start getting early feedback on how to make things better.