OOps. I thought my post had a mistake, but I read it 3 times and it looked right. I meant auto-import.
If you created the zpool from the GUI(like you are supposed to) then it will automount the zpool on bootup every time. If you didn't create it from the GUI(or had to do a reinstall of FreeNAS without a config file restore) then the feature you are looking for is "
auto-import"(not auto-mount as I said before). In any case, if you are having to run commands at the CLI to mount your zpool then you are doing something wrong(or not doing something right).
There are some circumstances where I don't think auto-import works. If you are in this boat, then I'm not sure what your options are. As a general rule, if you created the zpool from the GUI, then the zpool will automount on bootup and will work with auto-import.
If you didn't and auto-import isn't working, I have no good options for you. It actually is pretty important that the zpool be in the FreeNAS configuration and mounted automatically through the GUI to provide proper monitoring for zpool problems. You will need to destroy and recreate your zpool so that it shows up in the configuration and is properly monitored by the middleware. If you don't care because you are going to regularly monitor the zpool yourself(I wouldn't recommend this to anyone) then you could setup a cronjob to run
zfs mount -a on bootup. Just read up on cronjobs via Google and I'm sure you could have it setup to run on bootup in less than 10 minutes.