If I had to place one search priority above all else, I'd say right now, Google's most ambitious project is the knowledge graph. Yea, they are pushing Google+ big time, but the knowledge graph is a level above all of that technically.
Of course, Google has an outstanding team working on this project lead by one of the smartest people I've ever met Amit Singhal.
To take the knowledge graph to the next level, Google has hired/acquired Geoffrey Hinton and his team at DNNresearch. Geoffrey posted a note on his Google+ page about it:
Last summer, I spent several months working with Google’s Knowledge team in Mountain View, working with Jeff Dean and an incredible group of scientists and engineers who have a real shot at making spectacular progress in machine learning. Together with two of my recent graduate students, Ilya Sutskever and Alex Krizhevsky (who won the 2012 ImageNet competition), I am betting on Google’s team to be the epicenter of future breakthroughs. That means we’ll soon be joining Google to work with some of the smartest engineering minds to tackle some of the biggest challenges in computer science. I’ll remain part-time at the University of Toronto, where I still have a lot of excellent graduate students, but at Google I will get to see what we can do with very large-scale computation.
I know we just scratched the surface of the knowledge graph and I am excited to see where it takes us in the future.
I am just glad I don't have to figure out how to get us there. I get to just sit and enjoy the ride.