How can I perform the swipe gesture for quickly accessing Notification Center?
You might wonder why a two finger gesture on the trackpad from the right edge to the left edge doesn't always allow you to quickly access the brand new Notification Center in Mountain Lion.

Apple's instructions state:


  Swipe to the left from the right edge of the trackpad to visit Notification Center anywhere in OS X. Even from a full-screen app.


What they actually meant was a swipe gesture starting from the very edge if not outside from the right side of your trackpad and then finishing on the left side within you trackpad. This is easier on a notebook trackpad, you can start on the wrist area and swipe in, it's harder on an external one tho.

If you start too far within your trackpad you won't be able to perform the gesture for quickly accessing Notification Center, or you will trigger the page forwards/backwards gesture instead.