Short sleeve shirts are definitely not out. They are getting real popular again now after a couple of years of being not so hot. It depends of course what type of short sleeve shirt we are talking about but in general, they are very nice.
FWIW, I'm not American and I think that most Americans dress like [censored] and don't even know what fashion is all about (no offense, I'm sure some of you are in to fashion and are great dressers).
Here is one from Neil Barret that I really like:
