I've been traveling around for several weeks with a 3g iPad through India and China. Besides being intimidated of pulling out it in many of the spots visited, its been a great way of dropping weight (using digital copies of guidebooks) and navigating through cities. more on cutting sims, digital guidebooks, topping up, and other experiences related to traveling abroad with an ipad...
http://brandonshigeta.com/blog/2010/04/30/traveling-with-an-ipad/
http://brandonshigeta.com/blog/2010/04/30/traveling-with-an-ipad/