Even though it's an unofficial plugin, it's the only community plugin I could find for using Knife to . Maybe the commercial deployment of Chef has one. Here's a description of the plugin:
This is the unofficial Opscode Knife plugin for ESX. This plugin gives knife the ability to create, bootstrap, and manage virtual machines in a VMWare ESX/ESXi host.
You’ll need an ESX(i)4/5 host with SSH enabled and a privileged user account to connect to it via SSH:
You’ll also need a base VM template (a VMDK in fact) with CentOS/Ubuntu/Fedora and vmware-tools installed.
If you're using ESXi and Chef, go ahead and pick this plugin up so you can create, delete, and list your VMs with Knife. And be sure to check out all of the other community-built plugins for Chef and Knife.