This video was released today, and he basically says that all of them don't get acted on. Watch the YouTube Video: http://www.youtube.com/watch?v=e2QapzGmMjI
I think the point that they are trying to get across, as they have said in the past is that they do not generally issues penalties to specific sites what they do is look at what the webmaster is doing and try to fit a global penalty into the overall algorithm. If the site is unique in its spam etc.. then they will treat it directly or if it has large amounts of traffic or PR or a big brand name it will also be dealt with as a seperate case.
Good summary Gazzerman, this is why it confuses me when people say that they have been individually penalised, this is actually very rare. But as you point out it is the collective approach that google opts for.