Oh? I thought that worked. Well, coming back to the original poster's automation wish,
PDFtk can edit PDF metadata. It is commandline and cross-platform, too.
So if all your PDFs use a given naming format (say "author - title.pdf") automation would be possible. The script would have to do
1) pick apart the filename and store the results in a temporary text file formatted as follows:
InfoKey: Author
InfoValue: <AUTHORNAME>
InfoKey: Title
InfoValue: <BOOKTITLE>
2) Update the PDF metadata with pdftk's update_info function
3) delete the temporary file and restart from (1) with the next book
As long as your PDFs are named in a consistent fashion this would work.