PDFs are basically PostScript, and people have used Template Toolkit (and probably other things) to generate PostScript. Then you pass it through something like ps2pdf. I believe in some cases the relevant part pf PDF is plain text, so you can actually do it just like HTML.

If you ever find something that you can't generate simply with a template, you just need to change your application a little to support views being implemented in different ways, i.e. this view uses HTML::Template and this one uses PDF::Reuse.