For those who don't want to download the entire Java Development Kit (which is a reasonable decision if you're not planning to do any Java development — it's quite a big package), I've made available a compiled version of the compiler which should run on any system with at least version 1.3 of the Java 2 Runtime Environment. I've only actually tested it with Sun's Win32 JRE, but it should hopefully work elsewhere too as s2compile doesn't really use any advanced features which wouldn't be implemented in a standard runtime. A wrapper perl script is provided so that UNIX people can put it in their PATH and run it more easily, but because the package was made on a Windows box you'll have to set the execute permissions on it manually.
Also included are some syntax-highlighting definitions for TextPad and CoolEdit. I've never actually heard of the latter until today, but its syntax stuff was easy so I hacked one up. I was going to do Emacs too, but I really didn't feel like writing any Lisp code. Perhaps someone else more familiar than me can adapt a Java or C++ mode into a S2 mode for Emacs. Definitions for other editors are welcome too; once I've got a fair amount I'll put them up separately rather than bundling them with the compiler.
The compiler is pretty self-explanitory if you understand roughly what's going on with S2. The (albeit a bit LJ-specific) old docs are still up if you need to read something. In particular, there's my old language reference which is a bit outdated but should help with anything that you can't learn from the stuff that's already in CVS.