Well, when you include modules like lfs (Lua File System), lua SVN,
luasocket, etc., I'd wager that you could indeed do more with Lua than
you could with CMake (or at lest in a more unified fashion without
having to resort to shell scripts and such). I may be wrong though.
Does CMake allow for the programmatic searching of files in directory
trees or allow updating of files from a repository?
I don't have much experience with CMake or Premake, but my first impressions are that CMake's script is ugly as hell.
I was not very impressed by CMake either. It obviously has an edge over Premake in terms of maturity and features, but I feel confident that a group of 2-3 advanced Lua users could design a superior build tool based on Lua (drawing ideas from Premake, SCons, CMake, qmake, etc.). I myself felt tempted to start such a project ;-)
Premake is interesting, but not as extensible or powerful as one would expect. It does not support advanced build steps and does not have "extensions". For instance, it's unable to build applications that use Qt (a must-have, in my case).
I have previously used QMake, Ant, and am currently using SCons, but I've found it overly complex and way too slow for medium-sized projects. A mix of Premake, CMake and SCons based on Lua would come in handy.
-- Thiago
