The 3.5 GHz International standard is not available in the same bands in the US.  That spectrum range in the US is allocated for military purposes.  There are significant amounts of Fixed WiMAX product already being shipped in this range for the international market.  In fact all early WiMAX Certified products served these bands.  The FCC did open a lightly regulated band at 3.65 GHz which now has WiMAX gear available for it.  This band is offering a lot of opportunity for independent broadband wireless carriers. 

This spectrum range at 3.5 GHz is pretty much a de-facto International band.  The US really lacks commonly available licensed spectrum for broadband wireless purposes, particularly for rural applications.  Finding some additional spectrum will likely be a key challenge to the adoption of broadband wireless in the US for several years to come. 

It should be noted that the FCC has on occasion allowed what are called "Experimental Licenses" to be utilized in the 3.5 GHz range, but this is on a case by case basis.