Fellow Internet enthusiast & head of the online travel meta search engine http://www.zoomtra.com/ - Vikas, brought to my notice ( through a comment on my previous post's reference to Google's usage of mass media to market it's products ) this interesting link of a blogpost on Google using OOH media to promote it's local voice search offering. The post captures an interesting scenario:
"Google is interested in expanding into all forms of advertising, including the $7 billion outdoor market -- billboards, that is. Perhaps it's purchased some billboard space, in the hopes of using its dynamic, auction-based ad-selling system to resell it at a profit. Until it finds buyers, it may be using the billboards to promote its own services"
You never know - next revolution in advertising could be "Billboards by Goooogle" !

Thanks Vikas.