10's of Millions of FaceTime Devices in 2010

I just finished watching the WWDC announcement and I have to say this line is the one that got stuck in my head.  Where are these 10's of millions going to come from?

The only device presented that is compatible with FaceTime was the iPhone 4.  But that only accounts for "6 to 8 million units," according to Yankee Group analyst Carl Howe, unless they updated their other devices like the iPod Touch or iPad and released them sometime this year.  However a very large product line, one which was not even mentioned during the keynote, and one that is already in place with the hardware available is the Mac desktops and laptop lines that will see the first outgrowth of FaceTime.  I am guessing Apple will release an update to iChat and integrate the two together to make this a reality.  And with FaceTime as an open standard there is huge possibilities for companies such as Skype to integrate their already large audience to a new platform, which according to some in the company, sounds like something they are interested in.  All in all I think this is the most exciting announcement to come out of the presentation and cannot wait to get my hands on a new iPhone 4!