I have 6 vsphere 5 esxi hosts, with 4 physical nics each. one is for the management network, 1 is for vmotion, and 2 are for the vms.
the mgmt network nic and the 2 vm nics all connect to my backbone switch stack.
the vmotion nic on each connects to a seperate switch, a cisco 500 12 port.
mgmt IP 10.1.26.X gateway 10.1.23.1 (one of the vlan1's IPs on my switch stack)
vmotion IP 10.1.31.X
This all worked well on my 4.1 hosts. when I upgraded them to 5.0, I noticed that i could not set a different gateway for the vmotion network, there is one gateway for everything. vmotion would not work, I could not connect to any of the other hosts this way. i had to connect an uplink cable from my vmotion switch to my backbone, and at that time I was then able to use vmotion.
The idea I would think would be that isolation is what you want for the vmotion network, but what do I need to do to allow this switch to be isolated and still work.