Just joined a heap of PDF files with pdftk output*.pdf cat output nov2010.pdf and got a 19.5MB PDF file.

From here found a working solution to reduce the size of the PDF.

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -dNOPAUSE -dQUIET -dBATCH -sOutputFile=nov2010_2.pdf nov2010.pdf

Resultant PDF was 1019.5KB

Ubuntu 10.10