I find that Xcode version 4 is a great IDE but I wish someone had told me a couple of things about it before I got started.
Adding a Framework or Library
Click on the project name. Settings appear on the center pane. Select a target. Head over to the Build Phases tab. Add library at Link Binary with Libraries.
The Build Output
The default Xcode build output is not saved under the project directory. If you want to do that, go to Xcode preferences, in the Locations tab change the Derived Data option to Relative.