Those who weren't watching the FotoBilder community probably won't know about this yet, but I've been putting up packaged versions of the S2 compiler for a while now. I've just put up a source package which includes only the perl-based compiler (that is, it doesn't have the old Java-based compiler and other wcmtools stuff) and also a standalone Win32 binary, thanks to a friend of mine who compiled it using the Perl Dev Kit from ActiveState.
The Windows binary version is huge because it includes ActiveState's perl runtime, so if you're on Windows but already have ActiveState perl installed go ahead and get the source package.
This will only be (mildly) useful for people writing S2 layers for LJ and need to test if they compile correctly. The tools for running sets of S2 layers with test data are currently severely out of date with both the S2 API and LiveJournal's S2 backend, so you won't actually be able to run LiveJournal S2 layers locally unless you've got the entire LJ server code installed and running. Sorry! (Don't sweat — LiveJournal will be able to compile layers directly on the server soon.)
(It would also be useful for people considering using S2 as a style backend for a completely separate application, but I don't think there are any of those just yet…)