It's only fair that Microsoft wants users of their phones to be able to video-call too, which is why talk of a WP7 app from Microsoft has reached dull-roar status. Blabbermouth employees and a leaked pic suggest it's coming. Updated.
Updated: Neowin's procured some more photos of the registry keys within Windows Phone 7, which mentions VoIP. You could expect that Microsoft's FaceTime-rival will use VoIP as their FaceTime rival, but obviously it's still unconfirmed. With Microsoft's strong interest in Live services, it could even be linked up to MSN Messenger. More on this subject when we hear it.