[babel] using tramp when tangling

[Maurizio Vitale <mav@cuma.i-did-not-set--mail-host-address--so-tickle-me>]

I'd find useful to use tramp syntax in the :tangle specification.
In my case it would be to specify sudo when tangling config files that
are supposed to go to areas not writable by the user running Emacs. 
Something like:

#+begin_src sh :tangle /sudo::/etc/my_config_file
...
#+end_src

other people might be interested in remote access to tangle targets.

Is there a way to achieve the above?

If I try to tangle the above, I get something along the lines that
"tramp cannot append to file". Would it be possible to have org-babel to
(optionally) tangle to a buffer and then save to file in one go?

Thanks a lot for the excellent addition to org-mode.

       Maurizio