Version 1.0 of the Center for Internet Security (CIS) benchmark for securing VMware ESX server is available. This is specific to version 3.x of ESX and covers the basic best practices of preparing an ESX server for deployment.
We've still got a ton of stuff that didn't make the deadline cut-off for the first version of the document in follow-on iterations, but it's a good start. Please sign up if you can contribute to making this document even better.
You can find it here.