Rebuild after Xcode update?

I'm currently using Xcode 2.2.1 and am having trouble building the Python 2.5 port. A little searching suggested I should update my Xcode, so I'm downloading the Xcode 2.5 image as I write this. Once I've updated my Xcode installation, what should I do on the MacPorts side of things? Is there some way to say "rebuild all" or do I just plow ahead with the Python 2.5 install and ignore the fact that everything else was built up to that point with Xcode 2.2.1? Thanks, Skip Montanaro