this is very interesting as i have been wondering as well. i have the iphone 4 and i used jailbreak on it and have mifi so the wifi option is the only way to go for me. i have the uni-body macbook that i enjoy and have been skeptical on updating to the ipad for travel and fun. i am going to wait for the second version of the ipad to come out around march after all these other look a likes come out and see what apple has to offer. what is another three months anyway after waiting this long.
I use mine every single day, for business and pleasure. My 3G is lightning fast almost everywhere. I own no other Apple product but the iPad truly is a wonderful little machine.