We'll be rolling out FreeBSD 7 when we see a bit more customer demand for it. There
are no compelling features in it until very recently, specifically the multiple IPs per
jail. However, that's quite a new and thus risky facility.
We don't see FreeBSD 6 as particularly out of date and it's quite well tested. People who like FreeBSD tend to be very conservative about preferred versions as well. Which FreeBSD 7 feature do you require?
We're probably now about due to deploy a FreeBSD 7 option, however.