Erik Lagerway thinks VoIP over 3G is a when, not an if on the iPhone up in Canada.
This is of course not going to happen until Apple updates their developer's Terms and Conditions. Right now Apple's T's & C's that the iPhone developers are working under are not yet written to enable the applications to deliver the voice over the 3G networks officially.
Apple's rationale I would guess is that so far only AT&T has come out with a policy to enable it.
I say--BUNK. Since the iPhone's content can be localized by country, so can the apps, since basically, downloading of a application to the iPhone is not really any different than downloading the latest Michael Jackson video or song from "This is It." That is of course unless someone thinks that Voice over 3G Apps are licensed by the Beatles' catalogs' rights administrators...