How to share directories b/n jails on 6.0?

[Philip Hallstrom]

Hi -

I've got a new 6.0 box and have setup some jails.  I'd like to share 
/usr/ports from the host, to each of the jails.

I tried mount_unionfs and while it worked, the box would crash if I did 
anything intensive (ie. compile a port).

Googling around and people say they are using nullfs okay, but the manpage 
ends with:

 	THIS FILE SYSTEM TYPE IS NOT YET FULLY SUPPORTED (READ: IT DOESN'T WORK)
 	AND USING IT MAY, IN FACT, DESTROY DATA ON YOUR SYSTEM.  USE AT YOUR OWN
 	RISK.  BEWARE OF DOG.  SLIPPERY WHEN WET.

But then I also some some posts suggesting this no longer applied to 6.0.

Advice?

Thanks!

-philip