New York Internet Hotspots?

Hi, my name's Alessandro and I come from Italy. I was wondering how to connect my iPhone 3GS to the internet in a city like New York. I mean, I cannot use the system I use in Italy when I'm out (via 3G with my ISP), so I'd like to know if there are, for example, a lot of free internet wi-fi hotspots to use with no additional costs around the Manatthan or in the hotel! Thanks, YANKEES!