I think the message that you get when you try to accept your own answer within the last hour of the 48 hour waiting period is poorly worded. The message is "You must wait 0 hours before accepting your own answer." Yes, I realize it is accurate, as it means "less than 1 hour" -- but still.
One could special-case this situation and reword that to something like "You must wait less than 1 hour before accepting your own answer." Or approaching the issue from another angle, if the message was instead worded like "You cannot accept your own answer until January 23, 2010 03:23:23" then there would be no need for the inaccuracy. Time zone display would obviously be a factor/complication in this one.
BTW, I am aware of the the other metaSO post on this topic, but there was no suggestion there of an improvement to the message, hence me starting a new thread with that intent.