Is this the beginning of the end for Facebook?

A recent report from Inside Facebook claims that the social networking behemoth gained a mere 11.8 million new users worldwide in May — over two million less than in April.

"What's the big deal?" you ask. Fluctuations happen, right?

Well, when you drill down a little further, the alarm bells begin to sound.

Prior to May, Facebook had been increasing its global base by an average of 20 million new users a month for the past 12 months.

But in May, Facebook lost almost six million users in the U.S. alone — yes, million — dropping from 155.2 million to 149.4 million.

It's the first time the U.S. has actually lost users in the past year.

Uh oh, Toto. It looks like Americans aren't Facebook fans anymore.

Have Americans finally embraced the stoic LinkedIn as their social network du jour? Have the computer-tethered brethren banded together and nixed the Facebook time suck from their lives? Or have the myriad of Big Brother-reminiscent privacy concerns finally spooked the horses?

We could speculate all day until the cows come home. But now we're seriously wondering if Facebook is headed in the same direction as MySpace and the dodo.

Have you (or anyone you know) given Facebook the boot yet? And if not, how do you explain the steep declines of May?