Just recently in the news, Linden Labs (the creators of Second Life) and IBM have announced that they will allow corporations to run isolated portions of the Second Life universe on their own administrated servers to cater their business needs.
I used to work at a company that was exploring the business uses of Second Life. Sad to say the subject has been so dead over here in Europe that this all seems a lot like something that should have been ready during the hype 2 years ago.
Not to mention, this whole setup sounds all to familiar to the way in which ActiveWorlds works; and a lot of good it did that.
For years, Linden Labs has argued that its sole hosting of the Second Life universe was a unique selling point, something that made it more secure, more reliable than its competitors.