Its been converted into framework in 7.0. Its can be found at following location.
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk/System/Library/Frameworks/IOKit.framework/Versions/A/IOKit
YOu can copy this binary to some other folder and then drag and drop to "framework" folder of your project in xcode.
Btw: I was able to get almost same functions as previously. So hopefully old functionality should not break. (fingers crossed)