My latest article for SLentrepreneur is an Op-ed piece on what I consider to be the four over-arching features that are needed for a virtual world to succeed. Hopefully this will generate some discussion. In truth, the article is like a book waiting to be written because each element could easily be expanded upon. So check out The 4C's of 3D's: How to Succeed in Virtual Worlds at the SLentrepreneur site.
Oh, and the four C's? Construction, Commerce, Constitution, and Communication. Go read more ;)