A DigitalPoint Forums thread has an image of an AdSense ad that has the titles styled in italics fonts. Here is a screen capture from the forums, you can click on it for a large image:
![Italics Google AdSense Ads](https://farm1.static.flickr.com/115/397590825_6e6587ac95.jpg)
As you can see, this is not the standard:
![Normal AdSense Ad](https://farm1.static.flickr.com/113/397593290_b8b9ff1bf2.jpg)
Several DigitalPoint Forum member said they have recently seen these ad styles around the web. So it appears that this may be a limited Google test and not a premium AdSense publisher modification.
Forum discussion at DigitalPoint Forums.