This will give you a root shell but there's not a whole lot else at this point until further developments are made.
[04:00:25] <[mbm]> http://www.multiupload.com/R6U2NEMXHI
[04:02:27] <[mbm]> http://www.multiupload.com/MJY8SS8BAB
.. there's the sdcard image
[04:03:10] <[mbm]> dd to an sdcard, wait for fastboot and then run 'fastboot boot uImage' with the previous file
[04:04:03] <[mbm]> when the kernel boots there will be a serial and ethernet device on usb
[04:04:29] <[mbm]> ethernet runs telnet and ssh
[04:04:37] <[mbm]> serial is a getty
[04:13:54] <[mbm]> usb ethernet on the nook is 192.168.2.2
So what you get is a new usb interface called usb0 (on both the nook and your linux box)
set the linux box's usb0 to 192.168.2.1 and you should be able to ssh to the nook on 192.168.2.2. root has no password. takes a long time to generate ssh keys so be patient. Also, its 5am here and I'm half asleep.. so hopefully this all makes some sort of sense.