This AppleScript will rename a folder of files to match the names of files in a reference folder.

This was created specifically to address the problem of using batch file processing that results in new file names created. For example, processing a folder of files with non-sequential numbering (such as 0901.dpx, 0903.dpx, 0912.dpx and so on) in an application such as Adobe After Effects will often result in the new files being numbered sequentially, and may need to be renamed to match the originals. Simply run this AppleScript and select the folder with the original files, and then the folder with the new files.

For more information, see http://blog.surrealroad.com/archives/2010/a-problem-of-numbers/