It is now part of the regular AdWords program. How ads end up there is a combination of CPC and CTR. So if you didn't buy your way in there that means that people really 'like' your ad, and that it is well written, causing a high click through rate. The other upshot of this is that you are quite probably paying less per click than some of the people below you if you moved up in the rankings through CTR. Good work! :)