New version (I think it'll be a final one) adds support for sshd - when asked for a root password, just press enter. I've also rebuilt busybox with shared libs to decrease size.
Code:
ebs@mbp ~/linux/kindle/usbnet $ ssh root@192.168.2.2
root@192.168.2.2's password:
#################################################
# N O T I C E * N O T I C E * N O T I C E #
#################################################
Rootfs is mounted read-only. Invoke mntroot rw to
switch back to a writable rootfs.
#################################################
[root@kindle root]#