The usual way to connect you host servers to the network is via NICs either inbuilt or adding cards, to link storage it can be the same for iSCSI or it can be Fibre Channel HBAs. There is an alternative to this using the PCIe bus! NextIO have just released their vNET appliance which allows you to fit a variety of cards such as 10GbE or FC HBAs and then share these with servers over PCIe giving speeds of 40Gb to the appliance, the virtual NICs and HBAs are then presented to the VMs for installation.

You get a simpler way to connect your servers, a way to increase the utilisation of costly cards and have central management of IO.