Apple has just confirmed during their iPad event today that the new iPad will indeed have support for LTE. iMore had previously heard 4G LTE networking was a go for the new iPad, and indeed it is. The new iPad will have 2 LTE models, one for Verizon, and one for AT&T in the US and Rogers, Telus, and Bell in Canada.
We have not confirmed whether or not international LTE will be supported. Due to differences in frequency bands, it appears as if LTE may be a North America only feature unless Apple says otherwise. What we do know, is that you'll be good for up to 9 hours of surf time on 4G, which is pretty amazing in itself.