It’s $19.99 at Apple’s Mac App Store and it weighs in at 4.08 GB.
It requires at least Mac OS X 10.6.8 or later and one of these Macs:
- 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)
There maybe a retail version you can pick up in an Apple Store or have it shipped to you, but for now this is it, just like with OS X 10.7 last year.