Over the past couple days, I saw at least three people report that they saw six or more AdWords ads at the bottom of the search results. So as many as 10 ads on a single search results page, up to four above the organic results and 6 below the organic results.
Click on the image to enlarge full size and see for yourself.
Google is constantly testing things out with ads, even more so than with organic results, at least it feels that way. So no surprise here.