The 16th of September has only one update so far, and that particular update did not take place in-game, either. Instead, it has to do with Club Penguin’s mobile app.
On the 16th of September in 2013 the My Penguin iPad app (now known as Club Penguin and also works on iPhone and iPod Touch too) was updated to version 1.2.1. There were no new features. Instead it only fixed bugs and contained some improvements to igloo editing, which was the big update in verison 1.2.
Want to see and learn more? Check out these pages about the topics mentioned above.