In addition to fixing 43 bugs (nine critical), Firefox 3.5.3 warns users if they are using outdated versions of Adobe's Flash Player. Mozilla simply tossed a notice up on Firefox's update page to inform people who might be using old versions of Flash unknowingly. That decision reportedly lead about 10 million users to download up-to-date software from Adobe's website.

Mozilla chairperson Mitchell Baker called the surge a "very high response rate," in a blog post Wednesday. Baker said that the percentage of people viewing the notification, and then following the link to update Flash is about 30%. She added that a typical response is about 5% -- so naturally six times that number is quite the reaction.

Mozilla may notify users about other expired plug-ins in future versions of Firefox, and the fact that people have been receptive so far is "encouraging" according to Baker.