The jailbreak tweak called Auxo did card-based app switching in iOS 6, and then Apple came along and fully implemented the idea in iOS 7. Auxo, which started as a concept that went viral online, was suddenly obsolete.
A successor to Auxo has been in the works for quite some time, and now it’s available for jailbreakers to install in Cydia. Auxo 2 doesn’t reinvent iOS 7 multitasking, but the tweak builds upon it by adding more controls and customization.