I know Google has the power to push these things but they still take time. So don't hold your breath for an Android device yet.
A HTC Dream (the rumoured Android-phone, supposedly the one used in the Android-video below) + Android combo would be my iPhone killer. The Android interface seems good and the HTC Touch Diamond is just as slick as the iPhone. And with Android being much more open than the iPhone, that's more or less a strike!
Android: http://www.everythingdream.com/android-demoed-all-sorts-of-i...
HTC Touch Diamond: http://www.everythingdream.com/htc-diamond-videos-from-htc-p... – it is running Windows Mobile, yes, but the interface, TouchFLU 3D, is largely a work of HTC.
Demo and real life products are light years apart in handset business.
Even if you're not developing software for it, it's a damned good phone (easily the best I've ever used in terms of sound quality, reception, and battery life).
AFAIK the development environment blows away that of any other mobile platform.
But there is that bit about forking out $99 for a signing key to use your own code on your own phone, unless you go the jailbreak route.
ALSO, I've heard from other parties that if you use the key to install apps on an iPhone, you can't make calls with it anymore. A current limitation of the SDK development process that will likely be fixed in the future, I bet.
In other words, you don't want to buy an iPhone because you think you're going to use Xcode to whip yourself up some simple apps and install them on your phone. The situation right now is suitable only to hardcore types.
The point is, any prediction of Android's success will have a wide margin of error. I think the chances that Android will be better than the iPhone in the next 2 years to be very slim.
Get both. iPhone now and/or in July and Android whenever they come out in 2009, 2010, or 2011.