FaceTime Mac/iPhone4 question

So i understand that facetime between iphone 4 and iPhone 4 utilized wifi and actual cell mins (i.e. you call someone then use wifi to connect facetime). Now that apple introduced FaceTime for mac and iPods, i know that they call each other via email instead of cell mins.

My Question is, is there any way of facetimeing iphone to iphone via email as well? For example, Im in canada and if i have a friend in japan, to call via facetime would cost me a bundle in long distance mins, but is there any way to call via email so that i can facetime without using my mins and not pay long distance?

You can use your iPhone to call your friend in Japan without paying long distance charges. All you have to do is go to your contacts. Under contacts, there are options like text message and facetime. Just press facetime from there to initiate the call, no cell minutes or long distance minutes incurred.

I usually call my friends, even locally, from contacts so I do not even use any minutes.