There's a sense of presence. We have found that this is addictive and very compelling. The Virtual Worlds Group has worked on both graphical chats and virtual worlds. Virtual worlds have persistence, or a sense of history. This takes us beyond synchronous chat to a world that can evolve, a world that has a life and an existence both when we are there and after we leave.
Virtual worlds can have neighborhoods with distinct personalities.
Links can exist, allowing people to move back and forth between virtual worlds and the Web. Virtual worlds can give social context to shopping or information browsing or other activities we might want to do on the Net. Statistics indicate that people spend a tremendous amount of their time online socially interacting with each other. There are a number of trends that are pushing us to make the Net a rich social place. I will oversimplify to make my point quickly.