It depends on your search preferences.
Sweezely is correct. ;) More ads have shown for a while now.
Rugles, if you want to check (or change) you preferences, you can do so from a link labeled 'Preferences' on the G home page, just to the right of the search box. (Or, to the right of the search box on any page, now that I think about it.)
If you want the minimum number of ads, then set your preferences to "Display 10 results per page". This will give you 10 search results, and up to 10 AdWords ads (including the two possible at the top).
AWA
I much preferred this system as it led to a cleaner looking search results screen, and it prevented AdSense publishers from trying to do arbitrage by bidding $0.05 to bring in traffic in the hope that they would get clicks on high-priced AdSense ads. But I know Google will never go back to that policy.