Last week I blogged about jumbo frames being unsupported in ESX 4i.
Yesterday Charu Chaubal, Sr. Technical Marketing Architect at VMware blogged the following;

I am happy to say that this is merely an error in the documentation. In fact, ESXi 4.0 DOES support Jumbo Frames on VMkernel networking interfaces. The correction will hopefully appear in a new release of the documentation, but in the meantime, go ahead and configure Jumbo frames for your ESXi 4.0 hosts.
Although Jumbo frames being unsupported might not be an adopion blocker, this is quite good news for companies willing to use ESX 4i.