ZFS, booting trouble

[Ruslan Yakovlev]

Hi

I install 8.2-RELEASE root on ZFS with GPT and all works fine if I don't 
use zpool export.
FreeBSD can't boot if bootable pool exported (when we unmount zfs after 
installation finished or when we connect disk to other machine for data 
copy):
gptzfsboot: No ZFS pools located, can't boot

Now it can be fixed (zpool imported) only from other machine/OS/boot device.
Can bootable pool will be protected from full export?