Since Thursday 8/11/11 some of my clients have seen a reported 20 to 150% increase in traffic from Google in their analytics stats.
Sales have increased on some of those sites as well, which makes me think it's a real increase in traffic.
their pages per visit and bounce times have also gone to hell, but I don't know if it's a session issue, or just the extra traffic they are getting isn't as targeted as before.