Does FaceTime calls cost abroad?

Can someone from Apple catagorically tell us or is it documented, what the call charges are, if any, when calling abroad.
I would like to use UK to US.
I called orange my network who just keep on contradiction each other and frankly have no clue.
Alex

I believe the option to call them via Facetime only shows up after you have called them once and then did the Facetime switch (as it detects during the call that the user is an iPhone 4 user to enable the option).

Of course, with both on WiFi.

But after that first call, then you can go back later to the contact and just tap the call via Facetime option to call direct via Facetime for free.

Leave the phone in airplane mode. With older versions of the iPhone this is how I used Skype to make calls from many places around the world back to the States. I haven't been abroad since I have purchased the 4 but if in airplane mode it doesn't register on any carrier's network. You can connect to any wifi network with the airplane mode engaged. If it needs a roaming connection with the carrier the iPhone will ask you to turn off airplane mode. I wouldn't recommend doing that.

Once the facetime call starts, you are disconnected from your carriers cellular network, so your cell minutes are not used from that point on.

Or does it still cost like a normal international phone call?

No. See above.

According to my research (and it's pretty extraordinary that this is so badly documented), if you know the person you wish to FaceTime with is already on WiFi, go to their Contacts entry and tap the FaceTime button on the bottom right, the call will be connected directly via WiFi with no charges at all, like a VOIP call.
Of course if you start the call conventionally and then switch to FaceTime you will be charged for the first bit of the call.
It would be helpful if Apple made this clearer. I've made FaceTime calls in the UK where I've started the call conventionally and then switched. I'm in the US now and haven't used it, fearing high phone charges. It was only when I got an email today announcing the new iPod Touch with FaceTime that I realised it must be possible to use FaceTime exclusively as a VOIP app (since the Touch has no facility for making cellular calls...)

No, the FaceTime button appears at the bottom of every contact's page. Well it does on mine, even for people I know don't have iPhones!