Apple stores now selling iPhone 3G without a contract (US)
appleinsider.com
appleinsider.com
Presumably the current iPhone 3G is triband (850/1900/2100) as it is sold in Europe, Australia, South America, and North America. A quadband (850/1700/1900/2100) iPhone would work on T-Mobile in 3G, but there is little reason before 2010 for Apple to include 1700 MHz capability.
http://en.wikipedia.org/wiki/List_of_UMTS_networks#North_Ame...