What could "work Foursquare's data into Microsoft's products" mean? Spying? Pop-ups? Predictive Purchasing Pings? Thought-control?
I suspect it'll be the same as the deal they have with Facebook; integrated into Maps, Bing, and easy to check into places without using an app.
Well I suspect that might help with bing. Or else Microsoft wants to consider a check in app like google plus has.
Either way, it's useful geographical data which can be attached to reviews.