Since MtGox went down in flames a while back, I thought I'd go through and pull the trigger on trying to reprogram the Yubikey they sent me for free ages ago.
It turns out that it won't actually report an error until you try to reprogram it, but MtGox programmed them all with an access code that is required to reprogram it. This is actually a rather good security feature, but it makes the key effectively a relic now unless I can crack it.
Update: Someone leaked the access codes for most MtGox Yubikeys, meaning I was able to reprogram it after all. \o/