Facebook just announced that it will be opening up people’s photos and names to indexing (no doubt to squeeze more traffic and ad revenue) to Google, which will result in millions of extremely “thin content” pages getting indexed.
With no other useful information, I would say that most all of these will probably end up in the supplemental index. Actually, now that the supplemental label is gone, it will end up in the “little importance” index, which is probably still enough for it to get tons of no-competition long tail traffic (to monetize).
Flickr is a good case study for this – most of its millions of pages have a photo and little else and almost all of the site is supplemental.
Maybe Matt Cutts needs to talk to Facebook and let them know that Google hates thin content. But maybe it doesn’t matter when you have a PR8.
Personally I’m a little pissed off that Facebook keeps introducing these things by default and then tells me that I need to take action if I don’t want to partake in the gradual erosion of my privacy. Not enough to stop using it, but still.