I tried it here in KANSAS (midwest US) and I see differences too. I'm using title case and the results change. #2 goes to #4 and a site that is on the bottom of page two becomes #2. Wow. The results shift around for all caps too. I'm talking about organic here, not adwords.
Oh, even better, a search for GOOGLE returns different results than a search for google! ha! Also, in a search for Google a wiki article appears among all the google products.
[edited by: SEOMike at 2:43 pm (utc) on Mar. 6, 2008]