Have you ever used FreeBSD jails? I wish there was something as easy to use and flexible as that on Linux. The fact that each jail has minimal overhead and with dedupe on ZFS I can easily give every user their own "machine" while spending a lot less on hardware then a linux solution would require.

Having said that I also wish I could run FreeBSD on EC2 however I haven't put my money where my mouth is. I'm sure if you and many others wanted it badly enough you could sponsor development to fix any current issues. Also it would probably help if someone made a large business case to Amazon to ensure that things were targeted towards FreeBSD that would help too. (i.e. not needing an ext2 filesystem for the user provided kernel on micro instances, etc)