However, as a Canadian who has a US-based Google Voice number (Montana, eh) functionality is actually reduced on the iPhone.
Now the app initiates a call to a different US number (operated by Google) to then present the Google Voice number as the "who's calling" number.
This results in a long distance call. Before this, calls were initiated by calling the iPhone. Inbound = no long distance charges.
I can still initiate the old way by using the desktop browser instance of Google Voice on a desktop PC, but not from the phone because it auto-detects. Rats!
Oh well. I love the service and can't wait for it to be launched worldwide formally.
I change my user agent string, and everything works just fine. They use HTML5 things like local storage, and advanced CSS3 features, but Firefox has all of those things implemented.