[nznog] jumbo frames

Has anyone got any real world experience of the usefulness of jumbo frames on ethernet (ie, MTU > 1500 bytes). A number of 1000mbps interfaces support it, but it seems to be that it would only be useful if jumbo frames were supported and enabled on all equipment between the sending NIC and final IP destination, so I'm struggling to see how enabling it in just say the core of a network would be all that helpful.