I assume most of you have seen this Magic info – but just in case….

http://wizards.com/magic/magazine/article.aspx?x=mtg/daily/feature/42a

The Details: The procedure will work like this. Starting with the player who will take the first turn of the game and proceeding in turn order around the table, each player announces whether he or she will take a mulligan or not. Then everyone who said they would take a mulligan does so at the same time. (If no one’s taking a mulligan, the game proceeds onward.)

If any players took a mulligan, then just those players repeat the process to see if any of them will take a second mulligan: First they announce yes or no, then all the yeses shuffle and redraw at the same time. This continues among the mulliganers until everyone’s satisfied with their starting hands.

Once you decide you’re not taking a mulligan, your starting hand is locked in. You can’t jump back into the mulligan process later.