In this case, Sol's rig consists of a MacBook Pro with XCode installed, and VMware Fusion hosting both a primary development virtual machine with Visual Studio installed, and a handful of other Windows virtual machines (XP Home, XP Pro, Vista, etc. etc,) for doing regression testing of built apps.
Sol does a great job of doing a quick intro of how VMware Fusion can be used above and beyond just letting you run Windows on a Mac, but can even help turn your Mac into a serious development platform for Windows applications.
Sounds funny to the ear at first, but Sol, and lots of other users are doing just that, using VMware Fusion to take full advantage of their great Mac hardware, while using the power of virtualization to do things like snapshot and rollback to allow a clean base state for testing. Not to menion: finally getting Visual Studio for Mac!
Great post Sol!