Yes, the included effects can be used with pretty much any audio. I don't have any friends on Skype so it took me ages of pleading on facebook & twitter to find someone willing to let me call them and talk in a silly voice.
I would like to see some good managed audio APIs (or at least 'official' wrappers for the multitude of unmanaged ones), but as Dan says, there does not seem to be a lot of interest in it at the moment. Still, the number of .NET audio related open source projects
is gradually growing (check out VST.NET and livefft for two good examples on CodePlex).