We've seen clever jailbreak utilities for enabling toggles in the past, but I really think the developer behind Carnitine are onto something special. Carnitine, in this case, is a jailbreak tweak that can enable Wi-Fi while select apps are open and not the biological compound.
Carnitine is brilliant because it enables Wi-Fi not from the command of a gesture, a timer, or a GPS location, but from right when you open any set app. The idea is Wi-Fi is there when you need it. Though the implementation in the initial version isn't perfect, for reasons I will soon explain, I would love to see Carnitine expanded into a larger tweak...