AnkitMaheshwari - 8:04 am on Aug 27, 2010 (gmt 0)

What I have seen from my Google Webmaster account of different sites, if there are no one box (maps specifically) the CTR is generally 37-40% however with maps coming in organic CTR drops to 19-25% provided the ranking for the query is 1 in both cases.

I guess other webmaster must also be seeing some co-relations in the data.