Short answer: Yes, it's possible.
A little bit longer:
What comes to my mind at first is
pdftk, which can overlay a PDF file with another, see http://www.pdflabs.com/docs/pdftk-man-page/:
pdftk in.pdf background back.pdf output out.pdf
background < background PDF filename | - | PROMPT >
Applies a PDF watermark to the background of a single input PDF.
Pdftk uses only the first page from the background PDF and applies it
to every page of the input PDF. This page is scaled and rotated as
needed to fit the input page. You can use - to pass a background PDF
into pdftk via stdin.
If the input PDF does not have a transparent background (such as a
PDF created from page scans) then the resulting background won’t be
visible — use the stamp operation instead.
pdftk in.pdf stamp back.pdf output out.pdf
stamp < stamp PDF filename | - | PROMPT >
This behaves just like the background operation except it overlays
the stamp PDF page on top of the input PDF document’s pages. This
works best if the stamp PDF page has a transparent background.
At that stage it's not completely automatized, you still have to create the file
back.pdf by hand.
A possible automatic solution is to create a PS file with a template text at the desired position, search&replace that text (in un*x with
sed) with customer's name and process the result with
ps2pdf. [EDIT: See my second answer for a step-by-step howto.]
But I'm sure there are more elaborate tools... lot of scientific journals do exactly the same. One of those PDF files identifies its producer as
Producer: StampPDF Batch 4.1.1 Solaris SPDF_1116
So StampPDF seems to be a professional software for exactly that purpose.
I liked that challenge. So here's a step-by-step howto:
- Create PS template. That's a littly bit tricky, the text must be contained unaltered. (Export PS with Text as Text and do not include font -- phrasing as in CorelDRAW). Here is an example: stamp.eps