OS X 10.8 Mountain Lion is currently available on the Mac App Store today July 25th .
The current new features include the following plus some more less prominent ones.
- Messages – replaces iChat to bring full iMessage support to the Mac
- Notification Center – just like iOS
- Share Sheets – allows easy sharing of links, videos, photos between apps
- AirPlay mirroring – send wireless video to an Apple TV
- Game Center
- Twitter Integration
- Gatekeeper – anti-Malware app installation guard
OS X Mountain Lion is deeply intergrated with iCloud and iMessage. The new version of OS X, Mountain Lion, is now available in the Mac App store for $19.99 USD.