Lua 5.1.3 has been finally released. I downloaded the binaries from LuaBinaries only to discover that the Windows version has been compiled with Microsoft Visual C++. That means that one would now need to carry along three files instead of one: the lua interpreter, and lua51.dll and the runtime library for Visual C++ (msvcr80.dll)!
I recompiled the source code of Lua with Dev-C++ and now only one file is needed, just like the Linux version! I also compressed the two versions with UPX so that each one of them is around 65KB. You can download these two tiny interpreters from here.