Did you happen to see the afternoon match with Annika Sorenstam? On the 17th hole, she had what looked like spike marks in her putting line. She asked for a ruling and whether there was any exception if they were indeed spike marks. After a fairly long delay, the Rules Official ruled that they were spike marks. Thus, she would have to putt around the marks as Tiger said when Vijay Singh complained about Phil Mickelson's spike marks.
It was nice to see that rules are rules. Until the USGA changes the rule about not being able to tap down spike marks on putting greens in the Official Rules, there was no reason for Annika to receive an exception and tap down the marks. Neverthless, it was unfortunate that the person who created the spike marks did not tap them down.
So, in your next round, if you happen to create spike marks with a slip or shuffle of your feet on the green, be considerate and tap them down.