What technology stack is Second Life built on?

For example, are they using Java/Struts? Or ASP.N开发者_运维技巧ET? Or PHP? Or some combination of technologies?

Not sure how public they are about their infrastructure, but it would be very interesting to know what they use.

Not sure if this is what you are looking for, but see here: http://en.wikipedia.org/wiki/Second_Life#Technology

As is often the case with such questions, High Scalability has an overview of the Second Life architecture, plus links to presentations by SL staff and other resources.

I will take a wild guess, a combination of scripts running on a server written in C++.

While this is an antique question, I'm surprised that no one mentioned OpenSimulator or some other Sim application. OpenSimulator will allow you to run your own Second Life clone on your own hardware and with one of the many SL viewers that are out there, you could just connect to your own virtual world. And this World would be very similar to SecondLife, including it's scripting language!
OpenSimulator is written in C# back in 2007 using the Second Life Protocol to be very identical, although they don't strive for complete compatibility.
The Firestorm Viewer is also open source as Linden Labs once published the source code of their viewer using an LGPL license. But the Firestorm team doesn't make access to the source code easy to find. (It is here!) You will need to know C++ to understand the code.
So, Second Life is made from three parts: Server, client and a special protocol that goes in-between. As Second Life is old, it also uses some older techniques and protocols as developers generally don't fix things that aren't broken. Then again, this question is also old and I'm not even sure if anyone is still interested in Second Life.
Still, if someone is still interested then this gives some nice additional information.