Apple has released the first update to Mountain Lion, version 10.8.1, as of today. So if you’re one of the more cautious folks who never install the “dot zero” update, now’s your chance to pull the trigger. If you already made the leap, you can go to the Mac App Store and get your update from the Updates tab, or you can use the manual installer if you prefer. Either way, you’ll need to restart when it’s done.
As with all system updates, usual disclaimers apply here. You’ll need to make sure your other applications (and in our case, browser extensions) are up to date, and it’s always a good idea to have a backup of some sort before you click install, because you never know.