Starting last week, Google AdWords began promoting the first line description to the ad title of some of the ads. That means, sometimes an ad will have a really long blue link and a single line description.
Google said this "results in higher clickthrough rates for ads that are shown with the longer headline, as well as other top ads that appear beside them."
However, there are some unforeseen consequences of the change. Google does not allow exclamation points in the AdWords titles. But they do allow it in the ad descriptions. By dynamically moving up the first line description, Google is essentially allowing advertisers to break their guidelines and show these exclamation points.
Here is a picture of an example of one advertiser unknowingly breaking the AdWords guidelines:
So for now, as an advertiser, capitalize on this while you can.
Forum discussion at Search Engine Watch Forums.