Yes, it does work. You've probably done it wrong. You either have installed it wrong or you have not uploaded a cape.
How do I upload a cape?
Register an account using your minecraft username then click Upload Cape.
My Cape isn't showing
Make sure to have the mod installed.
I've installed the mod and uploaded a cape but I can't see a cape
Check the cape mod is show in the forge mod options and also make sure that your name on the website is the same as in game
I'm laggggggging
Make sure to dedicate at least 2GB of RAM. Also make sure your cape is not set to HD, try keep it at 64x32
How can I use with optifine?
Use forge, find the download on the Website.