Yep, this is a pretty lame ranking system. Projects are given more points the more people are registered in them with accounts on the system.
Compare this with what Ohloh does, where someone can be ranked in the top #10 of contributors (or projects) without even signing up.
Ohloh doesn't offer very interesting stats, so I was expecting something more for stats junkies, but this is considerably worse in most all respects.
It will result in Flickr-like interestingness numbers, where people who play in the social network have more ratings, rather than a system that identifies the most important projects or the most widely active developers.