Couverture Shelf Life

I have a block of Callebaut 70% dark couverture which shows an expiry date of late Aug 2011. Also a block of Callebaut 56% dark with the same date. They have been stored in a cool room in containers. What's the general rule for using chocolate that is over its expiry date? What about others like white and milk chocolate?

You should be fine. My experience has been that it is the milk fats that will turn. White chocolate has the shortest shelf live. I can keep that for at least a year if kept dry, dark and cool. Dark can be kept for years.