OY. Never even considered this one. There *should* be a way but I've never seen anything. Have you checked out mysql.org to see if they have anything there? If/when you figure out how to decrypt you can basically do anything with them.
Another option - not exactly an eloquent one - would be to send out a bulk mail to all your members that autogenerates new passwords for them and they just have to confirm the email. Messy, yes, but it would also allow you to notify them that you're changing the board script so they can re-bookmark you. Just an idea - and for every problem facing humanity there is a simple and eloquent, and equally WRONG solution.
