OS X Mountain Lion (10.8) is coming tomorrow and for those that still haven't check if their Macs are going to be able to run this version of OS X, here is the official list of Macs supported under Mountain Lion.
To see what is the model of your Mac, go to the Apple logo on the top left of the screen, tap on "About This Mac", then tap on "More Info...".
- iMac (Mid 2007 or newer)
- MacBook (Late 2008 Aluminum, or Early 2009 or newer)
- MacBook Pro (Mid/Late 2007 or newer)
- MacBook Air (Late 2008 or newer)
- Mac mini (Early 2009 or newer)
- Mac Pro (Early 2008 or newer)
- Xserve (Early 2009)