[AUCTeX] How to get pdf mode turned on automatically for beamer files

[Stephen Eglen]

By default, I normally keep tex pdf mode off, as for most of my
latex'ing I wish to use latex/xdvi etc.  But for files created
with the beamer package, I'd like PDF mode turned on, to make pdf
slides.  Its only a few keystrokes away (C-c C-t C-p) but how can
I get emacs to automatically turn on PDF mode for my beamer
files?

The manual says:
 -- Command: TeX-PDF-mode
     (`C-c C-t C-p') This command toggles the PDF mode of AUCTeX, a
     buffer-local minor mode.  You can customize `TeX-PDF-mode' to give
     it a different default.  The default is used when AUCTeX does not
     have additional clue about what a document might want. 

So, how do I give AUCTeX an additional clue that for beamer I'd
like PDF mode on?  Do I have to use a File variable at the end of
my tex file?

(I'd also like to have a keybinding turned on if beamer is
recognised, how do I do that?  Edit beamer.el?

Thanks, Stephen

Emacs 22.0.50 AUCTeX-date "2005-07-21"