Can you keep old images around please?
In order to have repeatable builds and homogeneous servers, it's necessary to have them all running the same variant of whatever distribution. With every new Ubuntu 12.04 point release, the old ones have been removed. This has caused problems because automated build processes simply stop working as they reference a deleted image. And now the simple act of bringing up a new server introduces inconsistency across a cluster of machines.
Perhaps a solution would be to hide them in the UI to prevent user overload, but still make them available via API?