The problem we have is persuading non technical decision makers of the merits and possible uses for the technology they've already paid for. We use HA/DRS VMware 4 clusters across multiple datacentres. Our SAN infrastructure is VMware aware but is not configured to use the functionality. We still need to 'ok' simple things like VMotioning a guest from one host to another during core hours due to the "risk". When you try to explain that we have DRS enabled on the cluster and therefore VMotion happens every now and then without us doing anything you just a blank look, followed by a "no, wait until a downtime period". In my experience, the technology is pretty sound. People aren't using it properly or don't trust it enough to make the most of what it has to offer.