Avoid complexity
Yes, I am also trying to figure out the same so that I can get rid of other virtualization methods.
Actually, I could not figure out to easily bind disk-quota and cpu to specific jails like in openvz (just set cpu, virtual swap and diskspace etc. pretty easily in command line, this is somehting FreeBSD needs to focus on, imho).
In openvz, a single command can allocate 2 cpu cores, 512MB guaranteed and 1024MB burstable RAM, and 1024MB of swap to a jail 1000 (they call it VE) to start on boot like:
#vzctl set 1000\
--cpus 2\
--vmguarpages 512M\
--oomguarpages 512M\
--privvmpages 512M:1024M\
--swappages 0:1024M\
--onboot=yes\
--save
Something equivalent would be great in jails. I know that jails is not openvz, so don't say this is a comparison between apples and oranges. I am eagerly looking forward to somehting like this to happen in jails ;-)