lilypond-book question

[James Bailey]

I have a question. Given this input file:
 \documentclass[a4paper]{article}
 \usepackage[pdftex]{graphicx}
 \begin{document}
 \begin{lilypond}
 \relative c' { c2 a'2 \times 2/3 { f8 e d } c'2 g4 }
 \end{lilypond}
 \end{document}

I was under the impression (according to AU 4.4), that I could do
lilypond-book --pdf myfile.pdftex (a new extension for me) and get a  
pdf of myfile.pdf

This doesn't work.

Firstly, lilypond complains that it doesn't understand this extension.
lilypond-book: error: cannot determine format for: lily-book- 
sample.pdftex

Secondly, if the extension is changed to .lytex, LaTeX complains that  
I'm asking to use pdf mode, but dvi mode was detected
! Package pdftex.def Error: PDF mode expected, but DVI mode detected!

If, however I attempt to run pdflatex myfile.lytex on the following  
input file:
 \documentclass[a4paper]{article}
 \usepackage[pdftex]{graphicx}
 \begin{document}
 test
% \begin{lilypond}
% \relative c' { c2 a'2 \times 2/3 { f8 e d } c'2 g4 }
% \end{lilypond}
 \end{document}

pdflatex processes the file just fine, and pdf output is generated.

This leads me to believe that there is some error in the lilypond- 
book that precludes use of pdflatex. Am I missing something?