Editor: The built-in command line utility Compact.exe that is included with Win2k and XP (and perhaps NT4) produced output that I found less than useful -- it was too verbose for my purposes (I wanted to generate a list of files, one per line).
I could have written a Perl or Awk script to translate the output, but as usual I have ulterior motives so I wrote a utility that will do what I want... the result: FindCompressed.
FindCompressed will search a directory tree for compressed (or uncompressed) files and report found items to a console window. The output is suitable for use by shell scripts or other utilities that can process standard output. The Exit status returned to the operating system is the number of matching items found