Many people seem to be asking about the Semantic Web. I personally am not a big Semantic Web kind of guy, but there are some core principles I can see as how Second Life could be created in to a web of meaning where people, groups, PRIMs, and SIMS had links to each other; but more interesting to the real world or other virtual worlds.
For example in Second Life there is a SIM Torino/Turin Italy. There is also a Torino/Turin Italy in Italy. That tells you little about the actual relationship between the two. For example is this just a name given to the SIM, or is it a Simulation, and if so where are they both located in their own universes.
By using tagged relationships better meaning can be established. For example you can place a shape on Second Life constructed of 4 points to say these are the four boundaries of the SIM in SL. Space is easy to manage in Second Life. This Square is Space in Second Life.
You can assert a "couple" saying Turin Italy in Second Life is in a given space.
RL is a bit more complex. Google maps will give you an area view and you can drop a complex shape over Turin Italy and create the couple
Turin Italy is in a given space
Panoramio - Photo of La Mole Antonelliana
Sites like Panoramio and Google earth have rich connections.
The thing is you can join Second Life up with Real World by asserting
Torino Italy in Second Life is a simulation based up the Real Torino
Now suddenly you have some intense information. Searches in SL or on Google can find simulations of Torina and the SL simulation can now get data in Google about Torrin.
My idea that the next step of Web 4.0 will involve Second Life being able to draw RL data and RL based applications will be able to draw down SL data. I am very excited also about Twinity as a model for how this could work even more directly.
Rober1236 Jua the Cyber Trekker of Second Life