Now that I wrote various tools that interop with VMWare, I started working on a VMWare Tasks Library, a managed C# wrapper on top of VMWare COM ViX API that makes it really easy to use.
I checked in basic functionality of connecting to a virtual machine host, restoring snapshots, powering them up, executing commands, getting lists of files in a directory and subdirectories, etc.
At my day job we developed a tool that uses VMWare to test installers (executes a cross-product of virtual machine snapshots and installers). I plan to take an alternate approach here and write an MSBuild Task to control VMWare, which could enable more flexible automation scenarios.
Update (2015)
Check out VMWareTasks on Github.