Today I updated my mac with the latest version of MonoDevelop, MonoTouch and the Mono-Framework. I also downloaded the latest version of XCode, version 4 (a nifty 4.5 gig do
you can install them side by side by doing so(I believe you have Xcode 4 installed):
Run the Xcode 3 installer
When you can choose the install location change it to the folder of your choice but not to developer
Complete the installation and open Xcode 3
done