Google Nexus: The device has built-in Wi-Fi and Bluetooth.
The new iPad: A higher priced version of the iPad allows access on Verizon, AT&T, and other 4G networks off Wi-Fi. The device also has Wi-Fi access.
Kindle Fire: The Kindle Fire does not have 3G access. It has Wi-Fi access only.
Surface: During the unveiling, Microsoft talked about the Wi-Fi capabilities. No information about possible cell connections has been released.