I did a little more homework since the servers are down. There are no cows to kill so Blizzard was right. What they did this time was make it look like care bears/my little pony in the whole secret level. Here is more info on how to get the mats needed:http://diablo.wikia.com/wiki/Whimsyshire
It has unlimited use and can be upgraded for the different game levels. Only one person in a party needs it and doesn't have to stay when the opening is created. All of the mats are white items and account bound so you cant vendor them but you can drop them (staff included). Some people have lost theirs because they were dropping all whites from their bag and now they can't get it back unless they do it with another toon and pay again.