Here's news on a 3G iPhone:
http://gizmodo.com/gadgets/macworld2007/rumor-3g-iphone-coming-227850.php
In areas where I get a constant 3G UMTS signal (many parts of L.A. and the Bay Area), my phone's performance while browsing has been decent. Pulling up directions on Google this weekend in L.A. was actually very fast.