It has been reported in a WebmasterWorld thread that the top blue AdWords ads have been removed from the Google search results page. It is however, surprising to see that some users will see the top blue ads and some will not. There are speculations that it is based on your ad clicking behavior. The top blue ads disappear when refreshed over and over again. Google is testing this and the results get back to normal, if you clear the cookies.
The quote from Webmaster thread :
"I spoke to my account rep. They are testing a new feature whereby when a user performs multiple searches and does not click an ad, the ads are all moved to the right side of the page. The rationale is that the user does not want to see the ads anyway and it lessens the chance of a poor prospect clicking on an ad. If you clear your cookies, the results will go back to normal."