Meh. There is ALWAYS something to learn. ;) Even if the application is minimal within FreeNAS.
It isn't really difficult or that hacky, but can't be done from the gui. The problems are with persistence across reboots, and possibly upgrades (not sure if rolling release leaves fstab now?), and general usefulness of things once they are mapped. Thus Anodos's question. There are gotchas especially around things like jails where this would be a common use case.
Here is a walkthrough of the bsd commands.
http://www.cyberciti.biz/faq/mounting-a-nas-with-freebsd-mount_smbfs/
google: 'mount_smbfs freenas', 'man mount_smbfs', 'freenas fstab'
You'll see where the others before have failed, and the reason why no one is writing a book and walkthrough.