SL is not original
I see SL being touted as a new idea all over the place.
A tinyass little US product (they went through several company names) called ActiveWorlds, which, in fact, still exists, has been around since at least a decade.
There were a bunch of us at one point (I recall 1000-ish continuous), but a change in per-user pricing structure from $20 a year (a pittance, really) to $20 a month, plus PR and technical difficulties (didn't get 3d acceleration until '01 or so, and it wasn't exactly "good" and this engine hasn't changed since) caused a lot of influential, or at least well-known figures in the community to leave.
There were public "building" areas, open to paying customers, and if you needed more control than these afforded you, you could pay extra and you'd be sold a server license for a certain amount of real estate and you could do with that what you wished. A very significant amount of that income left with the alienated users.
In their prime, they also had no difficulty getting companies to do in-world events, including at least 3 (that I'm aware of) movie launches.
I'm not certain how things are going lately - it's been over a year since I've logged in (there are limited-capability free accounts as well) but the last time I did, the framerates on my ridiculous 8800GT box were the same framerates I had on a GeForce 256 when they first added 3d acceleration, which, coincidentally, were identical to the framerates I had on an SiS integrated chip with no 3d acceleration capability whatsoever - about 5FPS, but no more than 20. The number of concurrent users at about 6PM eastern US was a small fraction of what I remembered. The list of servers had shrunk from an expansive list you could scroll down for several minutes, 90% of which were user-owned, to one screen, most of which I recognized as various servers owned by the company and the empty husks of their corporate relationships.
Sex and smut were a very big part of the community, of course. After all, it's the friggin' internet. But many of us built lasting bonds with other individuals and built a network of friends and associates that transcended our ultimate departures. The commercial undertakings were ridiculous and never amounted to anything worthwhile - probably not even a single sale or efficiency point. There was a thriving economy as people developed tools, utilities, 3d models, and other things and made sales amongst themselves. It deteriorated as the most prolific artists and developers departed, but it was one of the last things to go.
Hearing what I do about the technical situation at SL and knowing what I do about previous history of similar products, I can see them starting to venture down the very same road.
I certainly appreciate the network of friends and contacts that I built in the virtual world, and indeed I wouldn't be where I am now without them, but the amount of time it takes to build these relationships in the virtual environment is detrimental to real world activity - if things hadn't collapsed I wouldn't be here, either.