Wouldn't the next cycle be a better indicator? I am guessing it took a while for folks to get co-founders, work on idea towards a prototype, etc. -- all of which took longer than the past few weeks.
I discovered YCombinator several weeks ago in a blog post about the fbfund/YCombinator meetup written by a July 2008 fbfund recipient. A link was posted prominently on the fbfund Facebook page for at least 4 weeks. This was the only centralized place for fbfund discussion and updates so a lot of applicants checked it regularly and may have found their way to the YC website.
Maybe the demographic data destroys that theory though.
Thanks, PG!
Perhaps there were many groups like us who had thought about applying a while and spent time editing their application before sending in the last few days.
Pressing that button was in itself quite satisfying.