There's not exactly a lot of details on this one, but Business Insider discovered something of a surprise while touring Foursquare's New York headquarters for launch of Foursquare 3.0. It turns out that the company is already testing out an NFC-based check-in system at its HQ, which lets those with a suitable phone (such as a Nexus S) share their location simply by tapping it against a blue dot on the wall. Unfortunately, there's no indications on any plans to actually expand it beyond its own HQ, although you can bet that it's pretty high up on the list of inevitable things or the company.
