wheel - 12:47 am on Apr 7, 2010 (gmt 0)
A bit of a tangent, but related. My site has regained some of it's rankings over the last few months, but not #1 on every term (which is where I was until late 2009).
I suspect, but not sure, that by going from a dozen pages to 5K pages that I've diluted pagerank or linkjuice or whatever, internally in the site. And that's caused my site to suffer in the rankings.
Which is too bad - I've added all that content, it shouldn't lose ranking on the money pages.
This happened a number of years ago when I did something similiar, but the site eventually mostly rebounded (difficult to say exactly).
I admit that I could be completely wrong on this, I'm no PR calculation expert. It just seems that there's some cause and effect there.