1. High end WP7 device - Lumia 800. It looks promising.<p>2. MP3 Phone - An XpressMusic device. Some people don't care for data, and want a capable feature phone. Good camera, Awesome music interface. People have come to expect high-quality touchscreens - so if you plan on using a crappy resistive screen, don't. Build a slider with a comfortable hardware QWERTY instead.<p>3. Phone for the developing world. Ultra durable, ultra cheap. This market is the fastest growing, and building a device which greatest fits their needs will encourage adoption.