If you're a frequent iWork user, you might want to update to the latest version, which lets you to sync your docs with iCloud (so that you can view and edit on other Mac and iOS devices), and includes full support for the MacBook Pro Retina display (no more blurries!). 9to5mac says the update also includes support for dictation, which a new core feature of Mountain Lion.
But iWork isn't the only app to be updated. Cult of Mac says iPhoto also received a shiny new Mountain Lion upgrade, allowing users to share photos to Messages and Twitter directly from the app.
Safari meanwhile, now has a unified search and address bar (just like Chrome), offline Reading List support, and compliance with Do Not Track, according to The Verge. The Mountain Lion version also allows for the use of iCloud Tabs. [9to5mac, Cult of Mac, The Verge]