engine - 4:46 pm on Sep 17, 2012 (gmt 0)
As Google acquires more of these businesses it will start to feature more and more. It's becoming a portal for its own content, and no longer just other people's content.
The key part is that Google is in a very strong position, and that's what will make the advertisers and sponsors sit up.
As far as the SERPs are concerned, it's not actually in the organic SERPs. It's clearly marked, and above the organic but below the ads.
If Google had run it as an ad, it'd be less of an obvious own-property push.