wingslevel - 12:55 pm on Sep 27, 2010 (gmt 0)
i am also affected - main site gets about 35,000 uv's per week from organic google. has been at that level +/- 5% every week for over 6 months. i am ecommerce, so not too much facebook buzz...
for me, it has to be in the longtails - that is where i get 80% of my traffic - many of those pages don't even get 1 google organic referral per day - the other 20% are my "main" keywords - these tend to rank in the top 5 on very competitive terms, but they don't ever move - the longtail pages, most of which used to be in the old "supplemental" index, seem to fill up the rest of the referrals so as to reach my "cap". i am guessing that this may be easier to accomplish technically than some have speculated - a big part of the longtail formula is trust, which i think is domain-wide, so a little tweak on this knob could easily move tens or even hundreds of thousands of longtail serps up or down by a few hundred results.
a secondary thought, anybody have any sense of whether google products or images referrals fit into the "cap"?