[lurkerperpetual]

For those who care more about the underlying OS getting security updates for a long time, 8.04 is still the 'most supported' even if 2 years old. LTS releases have 5 years of updates for servers, so that means 2013. No other Ubuntu server release except the upcoming 10.04 one will be supported that much into the future even if more recent.

Add the fact that turnkey actually uses fresh packages for many appliances and uses only the kernel+base system of Ubuntu LTS, it makes perfect sense.