An announcement today by Google is a great first step in assuring individuals privacy. But their is a bit of a twist. Apparently they are going to have to hold the data for 18–24 months before they do what the refer to as anonymizing the log files.
So for a period of 18–24 months courts and Google can still review the searches you have made. This is not surprising but I bet that some over zealous official will introduce legislation that will require them to archive the data forever. Google Blog