Mozilla has released an eleventh beta of Firefox 4, which includes a handful of bug fixes, speed improvements, and a new "Do Not Track" privacy feature. This last bit is perhaps the biggest change, or at least the one Mozilla is talking most about . Firefox users can check a "Do Not Track" box in the latest beta, which is found in the "Advanced" screen of Firefox's options. When selected, a header is sent to websites alerting them you want to opt-out of online behavioral tracking.
"The Do Not Track header builds on the work the advertising networks have done to date without the cookie-based systems they make available to people online," Mozilla explains. "The advantages to the header-technique are that it is less complex and simple to locate and use, it is more persistent than cookie-based solutions, and it doesn't rely on user's finding and loading lists of ad networks and advertisers to work."
Mozilla acknowledges that this method requires both browser and sites to implement it if it's to be fully effective, a sort of chicken and egg problem, the browser maker says. However, Mozilla also says it's "committed to working with the technical community to standardize the header across the industry."