Not really. It's our Mac Pro workgroup server, running OS X Server 10.5.2. We've had quite a bit of fun with it, if by fun you mean "something involving two 802.11n draft wireless routers getting up and falling down, DHCP shenanigans, being confused about Standard and Workgroup servers, learning about Open Directory in, quite frankly, a bass-ackward way, but ultimately quite impressed at the level of integration".
Ben and I have spent the most time out of everyone playing with it, so here's the bits we liked:
The "Standard" server, with the quite ludicrously easy to use Server Preferences
Time Machine backups to a server AFP volume. Nice!
And here's the bits we didn't:
The "Workgroup" and "Advanced" servers which are so far removed from the Standard server that you actually have to sit down and read the manual(s) to work out what to do.
The obsessive hold OS X has to the Directory Server, so much so that Ben's Macbook Pro won't allow logins unless it's in the office (not much use on a laptop!)
Now, we know OS X Server is a Powerful Tool and Not a Toy, but really, it looks quite lickable and, for a few minutes, does a good job of pretending to be (relatively) easy to administer. We're not sure that the problems we're having (multiple 10.5.2 clients not being able to find, well, anything over Bonjour when using 802.11n) are related to the server or just 802.11n being quite crap in draft. It's hard to diagnose without changing everyone over to being a wired client, which just isn't particularly fun at all. It's getting to the point where we're going to have to Get Someone In to have a poke at it, because although it's quite working, it's not yet working perfectly, and for things like setting up VPN access (so someone can tunnel in and use RDP to a VMWare XP image - the only explanation I'm going to give there is "Sage Line 50") we'd much rather someone who knew what they were doing were, well, doing it.