At least not initially
Apple’s new iPad device will not be supporting FaceTime over 4G LTE networks despite it is being faster than Wi-Fi is you have good coverage.
TheVerge have confirmed by themselves that the new iPad (That releases tomorrow, officially) is not supporting Facetime connections over 4G LTE networks, the same way the iPhone did at first time with 3G. This means that as for now (and without jailbreak available yet) we can only perform Facetime calls over Wi-Fi until Apple decide to make it available with 4G.
According to TheVerge:
NEWS SOURCE: New iPad Facetime LTE (via) TheVerge
Our thanks to 'Kaos2K' for another news item!