We at Black Duck noticed it too. So far, looks like the decline is largely because, lately Ohloh - a) hasn't kept up with discovering new projects. b) hasn't paid needed attention to keeping existing projects up to date.
We'll provide more details once transition is over (we just acquired Ohloh from Geeknet).
We'll provide more details once transition is over (we just acquired Ohloh from Geeknet).