Getting updates automatically

[Randall Nortman <backportsorg@wonderclown.net>]

I want to make sure that I install packages from etch-backports in
such a way that the backported packages will be updated automatically
whenever the version available in backports changes -- to get security
updates, for example.  The mechanism by which the backports repository
prevents apt from automatically updating all available packages is a
bit of black magic to me, so forgive me if this is a stupid question:
If I install from backports via "apt-get -t etch-backports install
foo", will I automatically get updates to the backports version of foo
when I do a routine "apt-get update && apt-get dist-upgrade"?  Or do I
have to manually upgrade each package that I've installed from
backports?

I assume that if I use pinning in /etc/apt/preferences for each
individual package I want, then upgrades will work just fine.  But
that's a bit of a pain, so I'm wondering if the other method will also
work automatically.

TIA,

Randall