No the infuse 4G is separate. The SGS2 did pass the FCC with ATT bands BUT this was obvious since the early releases of the SGS2 in the UK have had ATT bands since this phone was revealed at MWC.
Anyone who wants this phone on ATT can just import it from the UK now anyways...lucky bastards.
I am hoping that they at least release the 32 GB and 16 GB versions at the same time in the US when they do...I do not want to have to wait around for the 32 GB version