As you may already know PhoneGap/Cordova 2.x has changed how the framework is referenced in iOS projects. This new approach gives more flexibility and ease of installation but at the same time it has some quirks especially when working in Xcode on multiple projects at the same time. This may actually change in the future releases as you may see there is an active discussion about it on the callback-dev mailing list.
In the meantime I wanted to share how you can quickly change a reference to CordovaLib directly from Xcode. The approach I prefer is to embed CordovaLib under my project directory. This way I can push it to my repository and version control it with my project files.