Get it while it’s hot, folks.
Be sure to read this little nugget of information from that page:
Whenever someone tries to reach you, the call rings through on every Mac you own even if FaceTime isn’t running. So you never have to worry about making yourself available. If you don’t want to receive calls, just turn FaceTime off in Preferences.
Very cool, but I have one big question — why is this not just part of iChat? Or will these two apps combine in OS X 10.7?
Update: The UI in FaceTime is very minimal, and very dark. It require an AppleID, and will let you create a new one right within the app. FaceTime can use an email other than your AppleID email, which is nice for those of us who keep using an expired MobileMe account for an AppleID name.