I guess THAT topic is again two years old; I was considering Isolator, but I also was looking for mocking across AppDomains. I was trying to use Microsoft Moles and it also has this limitation.
What I want to accomplish is mocking the .NET ConfigurationManager to run services that normally require configuration files, but setting up the configurations as part of the unit test, then hosting them on the stop so they all connect together just so (sort of like an integration test in the form of a unit test... maybe I should be shot?) Each service would run in its own AppDomain to simulate different configuration files, of course. I can make the whole thing work with Moles, just only in the current AppDomain.
Of course I can find workarounds, but this is a good excuse to have management buy us your snazzy-looking software :)