I was thinking about this for a couple of weeks now. After a lot of people around me were joking about my two Smartphones I was carrying around all the time (iPhone 3G and Motorola Milestone). After nearly 2 years of use, I decided to retire my personal iPhone in favor of my Android based Milestone. The dicision wasn't easy, but I think that Android has a lot of potential and I want to spent more time with this OS.
This doesn't mean that I give up the iPhone completely: I still have my company iPhone. Only for the case that I really need that specific App, which is not yet available for my Milestone.