Several aspects of LuaGnome are documented here. Should you seriously consider writing non-trivial software using LuaGnome, please read all of these pages (with the possible exception of the internal architecture).
A probably lesser useful documentation is automatically generated from the source code and specially formatted comments (LuaDoc). It is probably a mess and won't help much to write software, but might be useful when hacking LuaGnome.
As of May 2009, the following libraries are available (in alphabetical order):
Some terms used in the documentation may need an explanation: