Unless you’re living on a planet uninhabited by anything Mark Zuckerberg has touched, you’ve heard the news about Instagram.

Facebook, the biggest social networking site on the planet (our planet, you know, the one Mr. Z is on), purchased the mobile photo program Instagram yesterday, for $1 billion…all by themselves. And yes, that’s Billion.

What is Instagram? Essentially it’s a social networking program for mobile devices that connects people through photos. “Isn’t that basically Facebook?” you might ask. Yes and no. Instagram’s unique benefit (besides it being solely geared toward mobile devices) is its playfulness – it encourages users to take quirky photos which they can alter through various filters, then comment on and share with friends. Instagram’s photos feed into Facebook if you’d like them to, but until yesterday, it wasn’t actually a part of Facebook.

What will happen to it now? Unclear. All will surely be known soon.

But more importantly, what does it mean? In my view, the most important thing this acquisition tells us is that mobile is here – it’s not “up and coming,” or “on the way up.” It’s up. And it’s climbing. It’s fair to say, at this point, the personal interaction with technology is no longer the way it once was, and is vastly different even from a few short years ago. The New York Times’ Jenna Wortham writes, “The Instagram deal looks like something of a turning point, as even the Web giant Facebook tries to get a better grasp on a market that requires a rethinking of old rules.”

The days of PC first, mobile later, are over. And in fact, if you’re still living by that mantra, it’s likely that you’ll find yourself behind sooner or later. It’s time for a method change, and the idea of “adding mobile capabilities” can no longer be an afterthought.

I may risk sounding like a broken record here, but the mobile moment is now. Thank you Mr. Zuckerberg for putting your money where your mouth is and making us all realize that yes, this is for real.