There were an unprecedented number of cards handed out at the 2006 World Cup in Germany, besting the total from 1998. This year hasn't been as prolific. Through 25 games, there have been 8 red cards. In 2006, there were 28 through the entire tournament (64 games). In addition, there have been 83 yellow cards handed out as well. In 2006, there were 345 yellows.
While it seems unlikely the numbers this year will match these, several of the cards have been extremely questionable. Two yellow cards for "hand ball" against the US were given when the ball bounced off the players' faces. The game b/w Germany and Serbia was marred by 8 yellow cards and one red card. The red card given to Miroslav Klose in the 35th minuted was ridiculous. While Klose undoubtedly fouled the Serbian player, it is questionable whether his foul was cardworthy, especially given the fact that he was already on a yellow (another crazy card, but I digress). Serbia went on to score a couple of minutes after Klose had left the field.
Some of the cards have been deserved, see the red card given to Sani Kaita of Nigeria, many of them (both red and yellow) have been dubious. The criticism of the referees is not limited to their discipline record, look no further than Koman Coulibaly's terrible call that disallowed what appeared to be the game winning goal for the US. This subject has been addressed ad nauseum, so I don't feel the need to say anything more about it. Perhaps FIFA needs to rethink the way that selects referees for the World Cup. The only thing I know is that the biggest headlines (other than France playing worse than a Sunday pub league team, and England looking like a bunch of spoiled brats) have come from the poor officiating.