Happy Mountain Lion day! The newest iteration of OS X, 10.8 Mountain Lion, is available today on the Mac App Store for just $19.99. That $19.99 will buy you 4.05GB worth of operating system update – a large file, sure, but it is an operating system.

The download link is below, but before you send a Jackson on over to Apple, be sure to check out the following list to make sure that your Mac is compatible:

  • 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)

If your Mac is on the list – and you want to download Mountain Lion as soon as possible – just click the download link below and click the “View in Mac App Store” to purchase it. I personally haven’t experienced any slow server response in my downloads, so Apple seems to have done a pretty good job in preparing for whatever demand its customers have for 10.8.

Of course, that could change throughout the day, so let us know in the comments if you have any issues downloading or installing Mountain Lion!

Download: Mac App Store