Okay, so it was never on the Mac to begin with, but who didn’t see that coming? At Apple’s ‘Back To The Mac’ event this afternoon — or morning, depending on where you call home — FaceTime was announced for Mac OS X.  This means that all of those with iPhone 4’s just got a few million more potential friends to talk to via Apple’s suddenly ubiquitous social service.

Of course the most exciting news is that FaceTime for the Mac is available for download today.  For your convenience, we’ve included a video demonstrating a FaceTime call between a Mac and an iPhone 4. Check inside for the full details.

Will you use FaceTime on your Mac?  Do you think its prevalence will change the way we communicate?