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:

Yes, but not much you can do.

Forum discussion at Google+.