I'm backing out of this debate. I want to apologize, first off, for even bringing this topic up and debating it to begin with.
Each OS has benefits and downfalls, and as Android continues to grow towards it's third version, I'm confident that Google will bring it closer and closer to OS perfection. Windows 7 Phone's OS in my opinion is lesser only due to how Microsoft is choosing to handle its software - much like Apple and their iOS. You won't see very many apps from "Joe Schmoe" from Nowhere, USA on WP7 or iOS. The reason I love Android is that it allows anyone and everyone a chance to start a new application, build it, and distribute it.
Windows 7 Phone looks absolutely kick arse, much better than the iPhone, but it does what I absolutely loathe both Apple and Microsoft for doing. It keeps users out, so that only developers with larger resources can take a project to completion. Say Joe Schmoe has an amazing idea for the way his phone should work. Android is the only platform that allows him to easily create, test, develop and distribue his new idea with no limitations. Microsoft and Apple will keep him out of core functions or shut him down, especially if his idea fiddles with their baby's core OS. Take iOS for example. Currently, developers aren't allowed to go anywhere near making a replacement for the default music player. It's a case of "Apple knows best." Even if I had an idea that would revolutionize how we interact with our music on our iPhones, there's no way for me to develop it on any platform but Android.
I don't debate that WP7 is the best designed OS, or that iOS has "unity" down to a tee. Android is the only one that not only allows it's user-base to make infinite changes, it encourages it.