well i found a solution to this problem for who want to work with xCode 4. All what you have to do is importing frameworks from the SimulatorSDK folder
/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk/System/Library/Frameworks
i don't know if it works when you try to test your app on a real iDevice, but i'm sure that it works on simulator.
ENJOY
