Second Life just open-sourced their client browser. I agree with them that this move was inevitable (and smart), and I think it will lead to accelerating adoption as well as linkages of Second Life to 2D Web, "real-life" experiences (like MySpace, Facebook, LinkedIn, Yelp, Google Checkout, and the many others). We are already seeing many linkages to social networking profiles via ProfileLinker and others.
Again, Second Life may not be the 3D Web to survive – it is very early in the adoption curve and it all depends on their execution (the good, old basics of business). But this move should be the spark needed to fuel further interest in the 3D Web as the next-generation medium for shopping, browsing, and socially connecting. Just look at what happened with FireFox, based on the open-source Mozilla Project. It now represents over 4.5% of all Web browsers in use. That may seem like a small number, but remember how many people are online now (over 1 billion). And don't count the market-share leader, Microsoft, out in adopting the 3D Web.
At last year's Shop.org Multichannel Executive Symposium, Tony Lenk said that today's 2D Web is like shopping in a store one square foot at a time. I think that is a little extreme (site search from Endeca and Mercado, to name just one example, help you instantenously find what you are looking for as opposed to hunting for it in a store). But he makes a good point, and his recent DHTML enhancements to Gap were designed to make online shopping more tactile (and it paid off). Second Life and its 3D Web successors will definitely improve online shopping in a major way. Remember that scene in The Matrix where Neo says, "guns, lots of guns", and the endless row of guns comes streaming by in real-time? Kind of like that… but smarter. The key is adoption (wide availability and easy installation), speed (Second Life needs a heavy-duty machine and bandwidth to run well), and a relentless focus on serving their users well (Mark Cuban says it well).
If you missed my in-depth Word-of-Mouth Wisdom interview with Giff Constable, who builds a 3D, virtual presence for businesses in Second Life, you can read that here.