A few weeks ago, we reported Google was testing fav icons in AdWords results. The fav icons was a confirmed test by Google, that is still running to this day. In Japan, they seem to be really pumping up this test, by displaying much larger images near the ads.
A WebmasterWorld thread has a member reporting seeing 70x70 images. In fact, I contacted that member, and he posted the details, with screen captures at his blog, which is in Japanese. Here is a screen shot taken from his site:
Compare this with what we are seeing on Google.com, with just fav icons:
Huge difference here, a 16x16 vs a 70x70 image.
Let's not forget Google was also testing favicons in search results, the free, organic results.
Googler, AdWords Pro, confirmed the fav icon test recently in an Google AdWords Help thread, saying:
Google is always experimenting, and based on the limited information in your post, I believe you may be seeing one such experiment. If so, it is not a test that is generally available to advertisers.
Forum discussion at WebmasterWorld.