When I was at SES Toronto I had a good discussion with Todd Freisen about organic search engine placement. That night I made a draft entry in my wordpress for this post but I never added anything more. I often do that.
Basically the thing is this. Most of the time when people search they will only look at the top 3-4 rankings then scroll down to get to the next page. But there eye will catch the 9-10 result.. thus why sometimes 4-8 can yield suprisingly little traffic.
So I always tell people just get on the front page…. and dont worry about being #10