Sweet!
The first custom widget for iOS 5's new notification center have hit the jailbreakers popular free store cydia! The developer have made a new addon called UIsetting and it's very similiar to SBSettings plugin. It will install automatically and let you toggle between common used functions like WiFi, Reboot (respring), Bluetooth, Airplane mode etc!
If you are a developer and wanna make you're own custom third-party widgets for iOS 5 you should take a look at the source below:
http://www.redmondpie.com/first-third-party-widget-for-ios-5-notification-center-now-available-in-cydia-jailbreak-tweak/
http://pocketnow.com/iphone/first-third-party-ios-5-widget-available-in-cydia