If these are all public locations, wouldn't this pose duplicate/triplicate content issues with search engines? I'd think that giving the same blog post 4 different urls could be problematic on that score.
How about using subdomains with 301 redirects?
permanent redirects on each of the above urls to
The ability to navigate back to the source, I'd think, would require at least one custom home button that directed to an original referrer url. Maybe that could be tied into a session cookie?
Also, displaying content in more than one place is one thing, but I'm guessing that editing the dynamic database (ie. with the addition of a comment) would require a multi user interface.