Make a single file from the loose .po files from CVS
If you want to make a single po file from a CVS folder containing all the small po files, the following commands will do (*nix only). You should execute this (from a shell prompt) in the folder with the .po files.
$ msgcat --use-first general.po [^g]*.po | msgattrib --no-fuzzy -o nl.poOf course, you should change nl into your own language code.

single po file to multiple module files
For those of you looking to split the large .po file into its respective module files:
http://drupal.org/node/11311