My updated bulk file renamer script is listed here. (http://www.frontiernet.net/~nicholson150/file_rename.html) along with the Ruby source code.
I first started messing with this concept in this post, but have refined it a bit since.
Along with the Ruby compiler I mentioned yesterday, this could be compiled and dropped in your PATH somewhere (e.g. Windows dir), and then you could run it anywhere as if it were a native Windows/DOS command. I may end up doing that on my home PC to help rename the imported digital photos-- "DCP_05483.JPG" just isn't as descriptive as "Jeep Camping Trip 2007 - 012.jpg"