I'm quite interested in beginning some development using Amazon SQS, perhaps SimpleDB too, my question is this, are there any open source solutions that mimic the functionality, just for the purposes of development. I've already encountered the Eucalyptus project (http://open.eucalyptus.com) for creating an EC-esque cloud.

I've not had any success with google, I suspect it's because the cost of entry is so inexpensive, but still, does anyone know of anything like this?