A couple of corrections
Christa Lopes created the hypergrid integration part for OpenSim, not OpenSim itself. OpenSim is a open source project, similar to Apache, that allows people to create their own virtual worlds very similar to Second Life. (In fact, you can use the same browsers to access both.)
OpenSim is already up and running -- dozens of public world now use the technology, including OSGrid, ReactionGrid, ScienceSim, FrancoGrid, and many others. In addition, there are hundreds -- maybe thousands -- of smaller grids run by schools, companies, and individuals.
Anyone can download and install the software and run a virtual world on their computer, and anyone else can teleport in (if they know the hypergrid address). If you want someone else to host it for you, prices start at just $15 per region per month (compared to $300 for the same region from Second Life).
An enterprise version of OpenSim, integrated with enterprise systems, has been available from IBM since the summer -- it's called Lotus Sametime 3D.
-- Maria Korolov
Editor, Hypergrid Business