Looking at the code for that view, in
django.contrib.auth.views.password_reset, it appears that the actual
email creation and sending happens in the save method of the
PasswordResetForm, and the request is not passed into that method at
all so is not available in the template.
To make this work, you'd have to override both the view and the form.
It's not an unreasonable thing to want to do though - if you're keen,
raise a ticket with a patch.
--
DR.