I have written before about Google / Google Plus and their interactive, actionable ad units (here is a great example from Google Offers and one for Google's emailable ads here). Below is an example of Google Plus being integrated into an otherwise standard ad unit. Natural evolution and integration here - it sits atop the add and creates a social layer that:
1. The brands welcome. There is action and benefit beyond the click-through.
2. Google loves. They drive usage of Google Plus and give advertiser another medium to extract & measure value.
Should Facebook Ads move off-Facebook.com - these interactions will be really key (point 2 here).