Firefox 5 allows users to manually check updates for the installed add-ons. You can manually do a update check using the Add-ons Manager.
Click the Tools menu and select Add-ons from the list of available menus.
In the Add-ons Manager screen, click the Tools for all add-ons icon and select Check for Updates from the list.
This would start checking updates for the installed Firefox Add-ons
If any updates found then details will be displayed otherwise we will No updates found message as shown below.