One of Facebook 's (NASDAQ:FB) most attractive features is the ability to log in almost anywhere at the click of a single button. Those ubiquitous "Connect With Facebook" graphics make it easy to sign up for new services anywhere -- Facebook already knows its billion-name user list pretty well.

But there's a new game afoot. Earlier this year, Google (NASDAQ:GOOGL) introduced a similar sign-in program for its Google+ service -- and wrapped it in search-results incentives that Facebook has no way to match. If you want a top listing in Google results, you'd better allow Big G's sign-in method as well. That's a hugely important factor for modern Web designs, as Google drives enormous amounts of site traffic.

In this video, Fool contributor Anders Bylund explains why this might be the way Facebook's competitive advantage starts to disappear. Google isn't exactly out to kill the leading social network, but sometimes you have to step over a few dead bodies to reach your own goals.