[pdftex] Producing PDF/X-1a:2001

[Karl Berry]

    Is there a way in the TeX/Ghostscript world to convert to this 
    standard without resorting to Distiller? 

I haven't tried it, but how about:
ps2pdf13 -dEmbedAllFonts -dPDFX=true in.pdf out.pdf

(Despite the name, ps2pdf can happily read pdf too.)

    If not, could it be added to pdftex output without much trauma?

Again I haven't tried it, but I speculate that you could get PDF 1.3
output by setting \pdfminorversion=3.  I doubt there is any feasible way
to get PDF/X out of pdftex, though.