As of may 20th 2014 Nintendo Wii online functions (Beside shopping and videos) will be shutting down, this includes Club Penguin Game Day. If you own the game and want to get all of the unlockable items then it would be recommended to do so soon.
-Edit-
Here is the link to the source
http://www.nintendo.com/whatsnew/detail/vyWpoM6CBIe6FjW8NIY7bvzOrgBURhzw
-Edit 2-
Some people are saying game day is not on the list but if you read those listed are nintendo games and would not include a game that is made by a third party developer.