I don't think they've finished "connecting" some of the GUI stuff with the Plugins, Gcooper said the Beta-1 release was premature and not really ready to be posted.
For those of you that want to poke around inside the PBI jail (this is at the end of the video I posted in my blog), do this:
Open a Terminal/command windows from the GUI
Type "jls" (without quotes)
Look to see what the Jail ID is
Type "jexec -U root csh Jail-ID"
No you can do stuff inside the jail and it won't affect FreeNAS.
You COULD add packages etc. from here like a normal FreeBSD system with a few exceptions
If things go wrong, blow away the jail from the GUI and start over.
OH, to exit from the jail type "exit" and then "exit" again to close the Terminal window.
@dogmata, you can look at the mountpoint stuff using the steps above and then doing:
df (this will show what's mounted)
umount PATHname (pathname depends on what you see when doing df)
Also, with the jail you don't need to worry about doing a "mount -uw /" or only editing config files in /conf/base/etc, the jail behaves more like a conventional FreeBSD system.