Pete Meyers from Moz posted on Google+ that he spotted a new Google Answer for the search [interest calculator], which brought up a mortgage calculator box.
I personally was unable to replicate it and Pete said he only saw it come up once, but he grabbed this screen shot:
Pete's screen shot has a full view, showing the ads and full page of results.
Pete makes the obvious warning to webmasters in this area:
If you're in home finance, better take note. They're going to be stepping more and more aggressively into niche industries - we've seen it in credits cards, hotel, travel, insurance, and other.
Yes, but not much you can do.
Forum discussion at Google+.