Shares AT&T's Asus PadFone X will be available for pre-order online and in stores June 6, the carrier has announced.Like the PadFone Infinity, which was never released in the US, the PadFone X is a smartphone with a special dock that turns it into a tablet.It was announced at CESThe PadFone X will be up June 6 for $199 on contract, $22.92 per month with AT&T NextSmartphone in disguiseThe PadFone X