apt-get update and key problems

After updating my installation to etch I ran into a sligt problem with apt-get.

I just got an odd error message from apt-get update
GPG error: ftp://www.se.debian.org unstable Release:
The following signatures couldn’t be verified
because the public key is not available:

W: You may want to run apt-get update to correct these problems

Well, running apt-get update again (and again…) has no effect;)
What it (tries to) tell me is that the key used to verify the files in the archive was not found
The solution to this is simply

$ gpg --keyserver wwwkeys.eu.pgp.net --recv-keys F1D53D8C4F368D5D
$ gpg --armor --export F1D53D8C4F368D5D | apt-key add -
$ apt-get update

The wwwkeys.eu.pgp.net can be exchanged for any other key server that hosts the key, the only thing to note is that you should only use a key server that you feel is trusted.

Some info from Debian about this