Media Temple are running a beta programme for virtualized Mac OS X server hosting (Using Parallels Server)
This sounds really interesting, it would be nice to be able to rent a Mac OS X box and run services on it.
It might even be useful for things like running a build system or even as a testing server.
The question is how much will it cost. That isn’t entirely clear yet, apparently because they’re not entirely sure how much each instance will need in the way of resources.
(It must surely be more expensive, but how much more?)