Starting from Lenny, apt support the https transport for apt repositories.

Before, this would give the error:

# apt-get update
E: The method driver /usr/lib/apt/methods/https could not be found.

On Lenny (and unstable), install the apt-transport-https package:

apt-get install apt-transport-https

And https repositories will now work.

This is no current backport for Etch on, because the hack for the transport is quite intrusive and require some deep modifications in the entire apt code. Maybe another site will propose it ?

Note: it seems there is currently no way to check the certificate or configure trusted certificates. This is a good step towards security anyway. Remember: always use trusted repositories (signed with a trusted key - see man apt-key for more information).