Today, the best way to get an up-to-date version of XL is to directly fetch the source code using git.
% git clone git://xlr.git.sourceforge.net/gitroot/xlr/xlr
The source code contains two top-level directories:
xl2directory contains the front-end for the statically-compiled XL2 programming language.
xlrdirectory contains the dynamic XLR programming language
These two components can be built independently.
The compilers are currently only provided in source form. You need to build them before being able to write an XL program.
Once the compilers have been built, you can test them. In addition to verifying that the compiler works as intended, test programs provide a good source of examples.
Alternatively, you can also download it from the SourceForge downloads page. However, the packages placed there tend to be stale. This entry will be updated when any files worth mentioning will be posted there.