Just like in GameCenter for iOS 4, you will have a FaceTime username and password based off your Apple ID, and this username is changeable:

You will also get to pick what you want to show up as the Caller ID on the receiving end:

The following image confirms that your Apple ID will in fact be your main login method, and you can even create an account from within the FaceTime settings:

Now for the really interesting stuff… the behind the scenes action of BGR’s in-use screenshot of setting up a FaceTime e-mail account:

Now getting rid of your FaceTime account, which is not recommended as then you won’t be able to make or receive FaceTime calls:

Here’s some various account settings panes, and it appears you can simultaneously have multiple email addresses on one FaceTime account:

And finally, if/when FaceTime’s app gets a settings icon, it will look like this:

The iPod hasn’t a phone number but will have FaceTime this Fall.  This is why Apple’s using the e-mail method. If the next iPad has a camera, it will likely work in similar fashion.

This is actually pretty interesting because when it is all said and done, Apple users (and FaceTime is being Open-Sourced for other platforms) will be able to call each other without using a traditional or cell phone line.  Bad news for AT&T. Apple could theoretically put in a VoIP gateway and have a Skype-type of service within a year.  That would be interesting.