Well spotted.
Two GigE controllers and a 10GigE controller?
I'm sure that they're not all connected (as they'll require off-chip PHYs which might be quite expensive for the 10GigE controller, and they contend for SERDES ports with the PCIe controller), but these are nice things to have :-).
The ethernet controllers share the SERDES pins with the PCI-Express lanes. Considering what we're to believe about the rest of the system in terms of PCI-Express slots and onboard devices, I'd guess that nearly all of the SERDES lanes are consumed by PCI-Express. In the AW.net discussion I remember someone saying there was a Realtek ethernet chip on board as well, though I thought that one odd... Go PCI-Express to it, or use that lane for an SGMII to a phy, I'd go straight to a phy...
