It’s getting to be that time of year when pundits start making predictions about the hot technologies on tap for 2010. My favorite so far is less a prediction and more a reality that is happening right now. Mashable’s Peter Cashmore points out that Foursquare is the next Twitter-like social technology to break out, however I think his definition of the application programming interface (API) and its role in Twitter’s (and, eventually, Foursquare’s) meteoric success is even more insightful:

“This week Foursquare debuted the singular piece that launched Twitter into the stratosphere: an API. This application programming interface allows third-party developers to build anything they desire on top of Foursquare’s location-based social network.

It’s been shown time and again that once these ecosystems gain momentum, potential competitors face an arduous task. From Flickr to Google Maps to Twitter and beyond, it’s clear that early critical mass — having enough users and applications to make a service invaluable — sets the stage for a landslide victory.”