The world doesn't need another platform. Android is free and open; I think the only reason you create another platform is for political reasons. Why doesn't the whole world run with [Android]? They don't like the people who developed, or "not invented here," but [Android] is a successful, complete, vertically integrated free platform. I encourage everybody to use it, but I'm also not under the impression that everybody will use it, which is a good thing, because competition is good for the consumer and if somebody has an an idea for a feature or a piece of functionality in their platform and Android doesn't do it, great. I think it's good to have the benefit of choice, but in the end I don't think the world needs another platform.
Does the world need a better phone? Does the world need a phone that boots faster, a phone based on a web application framework, a phone that has a consistent interface? Just because Windows Phone 7 doesn't use Android, it doesn't mean that it's reinventing the wheel. Android is flexible, but it can't be used to build any kind of mobile operating system.
Millions of people will buy Windows Phone 7 phones and they'll find a new way to experience the Web. They'll probably use Bing, a browser that doesn't support HTML5 and they'll run Silverlight apps, but that's great: more people will buy Internet-enabled devices and will make the Web a better place. Great ideas come from everywhere and competition can only make Android better.