Club Penguin has unexpectedly updated the Snow & Sports Catalogue today, adding skateboards and other skating gear. They also made it so you can access the catalogue directly from the new Skate Park room. Also, while it was released in October, Club Penguin incorrectly put September on the cover. D’oh!
There are multiple pages of skateboarding gear as well as items for other sports. Check it out when you have a chance! Of course these items are all for members.
The catalogue at the Skate Park is exactly where you would expect to find it: the bottom right corner.
There are no hidden items.