By way of Search Engine Watch Moderator, OptimizeOnline, Google Launch Phase 2 of Longer Ad Text Beta Programme. Basically, Google AdWords will up the description character limit to 200 and then test the CTR rates of those ads versus the original ads. OptimizeOnline says that some advertisers will be invited to "beta test in mid-August and may continue it into October." The only variable that will be changed in these tests are the ad descriptions, the "the title, display URL, and destination URL of the ad will remain the same."
He goes on to explain;
Google will alternate showing the regular ad text with the longer version of the text. They also plan to experiment with slight layout variations of the longer ad text in order to determine which layout design will perform the best.
Charges will be the same amount when someone clicks on an ad – no matter what version is shown. The clickthrough rate of the longer creatives will be excluded from Quality Score calculations, and will not affect regular ads' ranking either positively or negatively.