In case you haven't heard already, VMWare Fusion 2.0b2 came out a couple of days ago and includes the ability to host Mac OS X 10.5 Server.
This news makes me want to cry with happiness. I've been waiting for this day for a long, long time.
Why is this so important to me? As a developer (and specifically an indie developer) setting up and testing my applications on a clean install of Mac OS X can be a pain in the ass. I'm not the type to have multiple machines for this purpose since I can't stand the clutter. Plus, once I've run my one of my apps on the clean system, it will leave little bits of debris around the file system in the form of preferences, caches, app support folders, etc. Sure, I could write a script to clean everything up; but that just doesn't make me as comfortable as a brand new install of the OS does.
VMWare Fusion makes this process super easy. All I have to do is install OS X once in Fusion and get everything setup how I want it before I run one of my apps, and then make a snapshot of the system. I can muck around with it, run my apps, do unholy things to try and crash VoodooPad, try out preference files customers have sent me, and when I'm done testing I can just rollback to the previous state with a click of a button. It can't possibly be easier than that.
I can also have multiple system setups for different types of testing, and do crazy things like test network communications between the two OS's without leaving my seat. Yes, I could do this with multiple machines and ARD; but why would I want to when a much more elegant solution was available?
About the only thing that could make this awesomer would be support for installing Mac OS X Client in VMWare Fusion. I know this is a legal thing that Apple is enforcing, but they really really need to rethink that. It's stupid to not have this ability.
In conclusion, VMWare Fusion FTW++++++!
If you're going to try out this goodness make sure to read VMWare's article "Installing Mac OS X Server VM and Optimizing Performance". You will also need a healthy amount of ram in your box.
P.S., why pick VMWare over Parallels or VirtualBox? VMWare beat them all to the punch with support for OS X Server, and besides; it seems like VMWare is quite a bit more "Mac Friendly" than the other companies. They were originally slower out the gate than Parallels, but they seem to get the Mac aesthetic in a way that Parallels or VirtualBox don't.
Also make sure to check out Joel on Software's article on VMWare from a couple of years ago.