It would be a great idea to get the iOS SDK working with cocoapods, a package manager for iOS apps.
https://github.com/CocoaPods/CocoaPods
It includes some popular libraries like ASI, Nimbus, etc.
It's a very slick way to ensure that external library management with xcode 4 runs very smoothly.
Here you go :)
Since they have no tagged releases yet, I currently chose a low version number (0.0.1).
Btw, the repo is nowadays located at https://github.com/CocoaPods/CocoaPods.