I’ve written about ELPA from the user’s viewpoint a couple of times. If you’re an Elisp developer and want to get your project into ELPA or Marmalade, Nic Ferrier has a nice post that details the steps. This is a good resource with details that I haven’t seen anywhere else.
Well worth a look if you’re considering contributing some Elisp code and want to turn it into an ELPA package. I expect that this will become more and more important as people start using the ELPA facility. I know that I’m already trying to get all my add-ons through ELPA and I predict that more and more folks will be doing the same.