Google was recently caught in the act of tracking and storing data from users browsing the web via Apple's Safari browser. Safari, the most widely used mobile web browser in the world, is the home browser of iOS devices such as the iPhone, iPad, and iPod touch, and is the default browser on Mac computers. Google's invasion of Safari's privacy settings for advertising purposes isn't ethical by any means.
Google produced an apology along with a promise to retract the invasive cookies after their loophole was discovered and confirmed. Apple knows that certain companies are sliding around the privacy settings that are in place and is working to keep the cookies out.
For detailed information, see Engadget's article.
