Apple Released Mountain Lion OS

What’s new :

  • iCloud support Improvement
  • Reminders
  • Notes
  • iMessage
  • Notification Center
  • Power Nap
  • Dictation
  • New Sharing features
  • Facebook ; Facebook friends will appear in Contact
  • Improved Twitter
  • AirPlay
  • Game Center
  • Gatekeeper ( similar to anti-virus )
  • Improved Safari

You can upgrade it simply by visiting Mac Store on Lion or Latest Snow Leorpard,

and availability on these Macs ( Other Spec required for the upgrade ) :

  • iMac (Mid 2007 or newer)
  • MacBook (Late 2008 Aluminum, or Early¬†2009 or newer)
  • MacBook Pro (Mid/Late 2007 or newer)
  • Xserve (Early 2009)
  • MacBook Air (Late 2008 or newer)
  • Mac mini (Early 2009 or newer)
  • Mac Pro (Early 2008 or newer)

For Details ; Source Official Apple Website