I know paradigm was trying to start scoophosting.com . I don't know what the status of it is, since it doesn't seem to be responding at the moment.
In regards to your other suggestions, I think they would be most easily implemented by adding modules to scoop somehow, so people could write those then just "plug it in" and have email, irc, whatever.
Adding them directly to scoop though shouldn't be too hard. Though I'm more of the mind to keep it like the unix philosophy, many small programs specialized for their own tasks.
If your going to do general hosting, it might be easier for you to take what some other people have done, and make a couple different parts to your whole website. Like have scoop.blah.museum be for the scoop stuff, email.blah.museum be for email, etc. etc., and all be different engines, specialized for each purpose. (like scoop for discussion, squrrilmail for email, etc.) Then somehow link all the databases to make sure they all have the same users.
-hurstdog
