Join Together v5.4 Released
Join Together automates the process of joining the files of selected iTunes tracks together with QuickTime and exporting them as a single AAC Music or Audiobook file/track. Optionally, you can then create a "chapterized" audio file of the exported AAC file with pointers to the individually joined tracks.
Version 5.4 of Join Together provides compatibility with Mac OS X 10.6 Snow Leopard, addresses issues with multiple libraries, and has minor GUI and performance enhancements.
More information and download is here.