The info on Gold cards is new, but mostly I think this confirms that Blizzard wasn't lying about the stats on rarity drop. It is nice, however, to know that approximately three cards in every two packs won't be a common.
I once pulled a Golden Onyxia and a Golden Gorehowl from the same pack with some other rare (that didn't seem important to me at the time) as well. ( I DE'd the Golden Onyxia for a Leeroy, and still have the Gold Gorehowl.) Can someone calculate what percentage chance that was? I'm thinking that will never happen again. (on a happy note, I let my Four Year Old, click those cards open for me...she was so happy about how excited I got.)
So I bought 15 pack today after work, and the results were ludicrous when compared to these expected values. Two Legends, and one Gold Legend in 15 packs. The best part of knowing these stats is how good it makes you feel to know you got really truly lucky.