What a (welcome) surprise. Although these changes enable me (and other developers) to use third-party tools to develop iPhone applications (i.e. Unity, MonoTouch, Flash CS5, etc.), I think I’m going to stick with using XCode. There’s no harm in knowing more than one programming/scripting language, and I don’t have to buy any software.
John Gruber outlines the major changes to Apple’s app store guidelines on his site. Definitely worth a read. Additionally, Engadget has the official list of what will be rejected. It’s nice to – finally – know what will be rejected before spending hours of development time beforehand.