I don't see the problem with this 3.1 update..
The complete jailbreak can be regained when you either installed usbnetwork before.
(besides that, the other hacks ss & fonts also enable the possibility to regain fully jailbroken again using an emergency.sh script).
What I did?
1) got my K3w 3.02 jailbroken
2) installed usbnetwork and made sure it worked, changed the root pwrd
3) backuped my /usr/sbin/otaup file (this one is changed in 3.1 to break your jailbreak)
4) downloaded the full 3.1 update bin (rather than wait to get the partial pushed) & upgrade
5) logged in using my favorite SFTP prog (that is transmit for os x) using my SSH credentials as root
6) renamed my new /usr/sbin/otaup file to: /usr/sbin/org_otaup
7) copy the old otaup backup back to /usr/sbin/ (after mntroot rw
)
8) chmod it to 755 (to make it executable)
et voila: jailbroken 3.1 with all keys working again
Don't even attempt to do this when you have absolutely no idea what I am talking about!
So if you are unable/find it too risky (which it is..): Wait until someone (else) makes a nice (safe) script for you which does the same.
(PS when you have SSH root via Wifi ; log in when your partner is using the kindle and give the command "jabberwocky" on the command-line. Fun if the volume is up
)