I don't see why people shouldn't just register their name of choice if they aren't already registered...having guest posting can allow some idiot to just come by and post crap.
I agree with BigBlue, no guest postings... too easy for even MORE B.S. to flow through this very nice forum. Probably be okay for guest posting at the OFF TOPIC forum (could be a potential incentive for future subscribers... another form of advertising ), since I don't look at that section very often... not to mention... off topic is off the topic and could be anything that blows your mind...