with the new (as of 2 weeks ago) pv-grub aki now avail, there really isn't much need for any vendor to get their own aki published. Creating an AMI has always been fairly easy, but only select people were allowed to create AKIs.
I have a fedora13 ebs-boot AMI I made and use; I could potentially make that AMI public, but you don't know me. I don't tend to use things from people I don't know, unless I've seen that a community review process has taken place, so I'd recommend either waiting for the ephemeral-backed AMI that others here are working on, or you can just make your own.
For an easy-to-follow setup (I scripted it while doing it, since it made it easier to fix things, delete, and try again), check out:
Note that it isn't supposed to be elegant/pretty/impressive, it's just supposed to be functional and create an EBS that, if you snapshot it, will boot and can be updated like "normal."
Brian