Google Adsense is well known for inspiring a buzz whenever they test new formats and features in their Adsense ads. This time webmasters are observing that the titles of the ads are in italics.
A DigitalPoint thread where some site owners have observed such ads on their sites.
I don’t think Italics titles will help get more clicks as it will break your blending with the content text. But on the other hand it might just provide that subtle difference (among multiple similar text links) which might attract a click. So maybe they want to test that out.