Okay, so the iPad with 3G will have GPS, and as it will run iPhone apps, it will be able to run Waze without any modifications. If Waze draws its graphics using a vector API on the iPhone, they might not even have to make a new version for us to enjoy hi-res maps.
Else, in the meantime, we´ll have to make do with the pixel doubling. Still a 9-inch GPS is cool, right?
Now we just need some kind of specialized car-kit for the device.. An iPad will not fit in my coffee-mug-holder, and it will block the view if I mount it in my front window.