Thanks for the great work hnak! I use your driver on 3 Mac Pro 10.8 Servers and it works great for me.
I have found one interesting glitch though and don't know if it is a driver issue or a VMWare one.
We use Fusion 5 and have Mac and Windows VMs running. Fusion defaults to using a virtual e1000 network card which works on Apples' internal ports but wont work on the i350t4 I have installed.
I've worked out that if I change this to e1000e, which is the default setting for Mac VMs but not windows, it works fine. Any thoughts as to why this might be?
Through all of this, the native Mac OS can see the NIC and use it fine.
Happy to help with any further testing you might have/need for ours or any other problems. Our MacPros are 10.8.2 w/64Gb RAM and dual 6 core xeons.