Security vs. Accessibility
A lot of noise has been generated around the CSS History Hack. Some people are skeptical about it and think that it can be fixed by installing the latest Firefox version. Others believe that IE is not effected. Unfortunately both groups are wrong.
Internet and mainly World Wide Web is designed to be accessible. Many different technologies need to work with each other in a transparent way. The user is the center of the universe and providing better environment for this center makes in theory more money for the service provider. All this leads to less security. A truly secure browser will ask you to approve everything it does, from launching popup window to executing a tiny chunk of code. However, this never will happen. Clicking on thousands of alert boxes is far from what most of the users call fun. If you enforce it you better be prepared to loose a lot of users.
Security vs. accessibility - one of the very well known dilemmas we encounter every day.