I have not done this, but I am looking into it so I found this post. So far, I am attempting to setup a Fedora Core 8 AMI and if I can get that under my belt, it would seem that adding Moodle would not be that much of an effort. I am also looking into perhaps getting a package of tools, such as Moodle bundled with XAMPP and then making an AMI out of that. So far, I have not had the time to dedicate to learning this new, but important technology. The good news is that once one of us does it and makes a working AMI, it would seem like the rest of us could easily fall in step. There seems to be a growing library of public AMIs on the way. Such as this one.
I will let anyone know if I make any progress.