Today Apple released the 3G version of the iPad with built-in Wi-Fi and three available hard-drive capacities. The iPad 3G is now available in 16GB, 32GB, and 64GB, and are priced at $629.00, $729.00, and $829.00 respectively (each 3G model is basically $130 more than the non-3G versions.)
The cellular network enabled iPads require 3G service through AT&T. However, no long term service contracts are required. There are two choices for plans: 250MB/month for $14.99; or unlimited for $29.99.