Supported Devices:

MacBook Pro:
MacBook Pro (Aluminium) Mid 2007 or later
MacBook Pro (Unibody) Late 2008 or later
MacBook Pro (Retina) Mid 2012 or later

MacBook:
MacBook (Polycarbonate) Early 2009 or later
MacBook (Aluminium Unibody) Late 2008
MacBook (Polycarbonate Unibody) Late 2009 or later

MacBook Air:
MacBook Air (Aluminium Unibody) Late 2008 or later
MacBook Air (Tapered Unibody) Late 2010 or later

iMac:
iMac (Aluminium) Mid 2007 or later
iMac (Tapered Unibody) Late 2012 or later

Mac Mini:
Mac Mini (Intel) Early 2009 or later
Mac Mini (Intel Unibody) Mid 2010 or later

Mac Pro:
Mac Pro (Cheese Grater) Early 2008 or later

Initial Release: 10.8.0 (July 25 2012)
Latest Release: 10.8.5 (August 13 2015)

New Features:
- Messages
- Notification center
- Discontinuation of MobileMe