If you start with any of the most recent released Ubuntu images , then Ubuntu Server
running on EC2 is really just that, a Ubuntu Server running on a virtual system hosted by
Amazon. For anything that you find that is different, please open bugs. The best way to
open a bug is to run an instance and run 'ubuntu-bug' on an EC2 instance.
The only real difference is that the bootloader is "pv-grub", which is really grub 0.97.
Ubuntu Server's bootloader would normally be grub2. In order to manage /boot/grub/menu.lst,
a package "grub-legacy-ec2" is installed.