VirtualAppliances.net are now using Ubuntu JeOS 8.04 LTS and OVF

http://VirtualAppliances.net/downloads/

VirtualAppliances.net appliances feature an upgrade to their base distribution, using Ubuntu 8.04 LTS Server Edition, which will be supported by Canonical until 2013.

All of the 32 bit Appliances are using Ubuntu JeOS (Just enough Operating System) which provides a kernel optimized for virtual appliance use.

VMware OVF (Open Virtual appliance Format) images are now available for VMware ESX and ESXi in both 32 bit and 64 bit versions.