Anyone who's using Lion with Time Machine and has an old NAS as a backup destination will have come across the issue with AFP using a new authentication protocol which probably isn't supported by the NAS.
(I have a not so old Buffalo Linkstation (LS-CH1.OLT) that still didn't work after updating to the latest firmware)
Anyway, I spent ages trying to get it to work until I came across this script which I'm re-posting as it was hard to find:
Basically, it hacks Lion to trick the new protocol into communicating with your old NAS.
More importantly, unlike the other workarounds I tried...it works!