There have been some interesting reports on the CTR of organic results, based on the leaked data from AOL:
[redcardinal.ie...]
[seo-blog.com...]

Here are the CTRs for being in the top 10 organic search results:
#1 - 42.30%
#2 - 11.92%
#3 - 8.44%
#4 - 6.03%
#5 - 4.86%
#6 - 3.99%
#7 - 3.37%
#8 - 2.98%
#9 - 2.83%
#10 - 2.97%

What I'd like to know is if there is an industry standard for CTR on paid listing (PPC) results? Or an average CTR for each position? Has anyone come across this information?