One of the side effects of the rapid release cycle of Firefox is that the hassle of updating, even in the highly automated process Firefox provides, comes once every six weeks rather than once a year or so. Mozilla is working on making the update process as streamlined and as invisible as possible.
To do this, Mozilla is aiming to have a completely silent update process for Firefox, as well as its other products.
What this means is that updates will be downloaded and installed with no involvement from users, at most, they'll be notified that the update process is undergoing.
But there are a few issues to overcome for a completely invisible process.
Windows UAC is an unnecessary annoyance
On Windows for example, users need administrative privileges to update Firefox, even if the process is automated.
This means that non-admin users will be presented with the Windows UAC dialog for each update. Mozilla wants to get rid of this unnecessary annoyance.
When Mozilla transitioned to the six-weeks release schedule, it was able to take the lessons learned by Google with Chrome the hard way and apply them.
Google Chrome also has silent updates. To get past the UAC dialog, Google Chrome is not installed in the Program Files folder, which would require admin privileges, but the user's app data folder.
Mozilla doesn't want to go down this path since it means Firefox will only work for the user that installs it, not a good solution for multi-user computers.
