We already have reality, and it's about as immersive as it gets.

Well yeah sure, but the knowledge to be gained by running simulations in a virtual earth are fairly sizeable I would think.

Or maybe use it to try rearranging your office furniture, demonstrate how new buildings will look, plan for disasters, town planning, the possibilities are endless.

Not to mention capturing historical 3D virtual snapshots of the earth at any given moment.

Instead of Second Life, I'd like to see a beefed up Google Earth world.... basically a Second Life style copy of the real world, where I can join you in a 3D copy of your actual office on the other side of the world.

Then on top of that, if you wished, you could add experimental fantasy world 'layers'. But a 3D VR (and very accurate) representation of the real world should be the first priority I think.