The UP! certainly looks like a decent competitor to the fiat but also doesn't look like it is available in the US yet.
It's a better car than the 500. I've yet to read a review that says that the Up! is anything other than the best small car on sale. Often by quite a margin, though that unfortunately includes the price too... unless you order the poverty spec version, which suits the ideology of the car perfectly if you ask me.
Autoblog have written one of the more comprehensive reviews that I've read so far, it's interesting seeing an American's view of the car. They seem to get it completely though.
I'd be surprised if VW weren't considering taking it stateside, you guys seem to be embracing small hatches more & more with each passing year. I wonder if VW are simply waiting to see whether 500 sales are sustained or whether they're simply a short term fad?
The only criticism I have of the Up! is that VW weren't brave enough to stick with the original concept, I think the production model suffers for being toned down, lacking the circular wings mirrors, wheel design and entirely glazed rear hatch. None of which would've been anymore costly to mass produce.