The update offers substantial speed improvements and over 200 new features including a new notification system, better support for multiple monitors and full screen apps, new redesigned apps like Contacts, Calendar and Notes.
This marks the first time Apple is not charging for a major update. The previous 10.8 Mountain Lion cost and nominal $19.99 and 10.7 Lion was US$29.99.
To make things sweeter, Apple is opening the update to all Macs running OS X 10.6 Snow Leopard and above.
During the keynote presentation, Apple took pot shots at Microsoft – Windows 8 costs $199.00.
Brace yourselves for very overloaded Apple servers.