in match play each hole is its own contest. Winning a hole will put you one up on the other golfer you are playing against. So if woods goes out and wins the first 3 he will be 3 up. then if allenby wins the next hole woods will only be 2 up. If the players tie the score remains the same and does not carry over. there is another post below on this same question as well.
they play until one player can no longer win the match. Say one player is up 3 holes with only 2 holes left to play. but it is based off of 18 holes. however as we saw yesterday they will go as far into extra holes as needed if both players are tied.