The next major release of the popular Firefox 4 will default to silent updates.
Apparently lots of users are not updating their browsers when Firefox notifies them to do so. That means too many people are running insecure versions of Firefox because most of the minor updates are security patches.
"For Firefox 4 minor updates will occur automatically," Firefox principal designer Alex Faaborg said in a post to the Mozilla Google group. "We'll only be using the major update dialog box for changes like 4 to 4.5 or 5."
You can read the discussion over this issue on the Google group mozilla.dev.apps.firefox.