I played quite a bit at the local card room this summer, and this is how they handled exposed cards.
Dealer exposes one card from starting hands: That card is shown to everyone and replaces the first burn card. The hand continues being dealt they way it should have (but one player only has one card) and then after everyone has two cards, the would be burn card is given to the player whos card was exposed.
Dealer exposes two cards from starting hands: The whole hand is reshuffled and redealt, the button and all blinds stay where they are.
Players expose mucked hands: They are warned and if the problem is persists, will be asked to move to another table or leave.
That's all i can think of right now, but i thought i'd give you the benefit of my experiences. Have fun!
Mark "Riverboat Willie" Nelson
http://viper12873.tripod.com