n vSphere 5 we have support for using multiple Vmkernel ports enabled for vMotion. Having more than one physical network card for vMotion allows us to utilize them simultaneous, even when only transferring a single virtual machine. If having spare NICs we could use up to 16 Gigabit cards and four 10 Gbit NICs just for vMotion. Having 16 extra network ports might not be too common, but the performance increase can be great when just adding another vmnic for the vMotion traffic.
--> Please see the rest on the blog : http://rickardnobel.se/archives/947