Running FreeBSD 4.9 Jails on a FreeBSD 5.2.1 system

[Kung Foo Ham[p]?ster]

I'm looking at upgrading my main system from FreeBSD RELENG_4 to RELENG_5_2.
I'll probably start with a clean sate for the system for that transition.

I have a few users who run their own systems on jails on my machine...

My question is:

When I install FreeBSD 5 on my system can I run those FreeBSD 4 Jails on it and
then upgrade them individually without much pressure.

I want to have as minimal down time upgrading my system.
I'm hoping that I can upgrade my system for a day and then upgrade the jails
individually at my leisure.

Can this be done?

-Adam