I work for the group that made Planet Hunters. We have a variety of similar projects at http://zooniverse.org, including four others we launched in the last month that have people classifying sea floor life, galaxies, cyclones, and bat calls.

They're very cool projects! I've been noodling around for a bit.

I'll register if I think I'll be any good, and I'll certainly be passing the URLs around to people if I think they'll be interested.

Could someone explain how that site works?

Are the amateur astronomers mentioned in the article user of planethunters.org who just happen to have been served the right pictures to work on? Is this Mechanical Turk type work or does it require serious scientific effort?