FibreChannel on Motherboard?
FibreChannel is a high-bandwidth data transfer architecture that is used by Apple to interface with its Xserve RAID solution. This requires an add-on Fibre Channel PCI card to be installed into the Xserve or PowerMac.
Of note, MacBidouille's articles have never indicated that these motherboards were for PowerMac's, and have always been described as the PPC 970 motherboards.
It seems unlikely (to this writer) that Apple would build-in FibreChannel into PowerMac motherboards... and could indicate a few other possibilites beyond the obvious -- including the possibility that these rumors are simply false. Alternative explanations might be that what is described is a new Xserve or Xstation motherboard (first mentioned here).