Way back in post #1 in this thread, I suggested that smart phones like the iPhone, some Blackberry models, Palm Pre and others should be considered slate computers. They include WiFi as well as 3G data modems. And they can run web browsers and other applications, in addition to being used as a phone.
The biggest problem with smart phones is their small screen size. The iPhone is typical, with a screen that measures 3.5 inches diagonally, and provides 320 x 480 pixels of real estate.
This is about to change. In February, Microsoft introduced its completely reworked OS for mobile devices, called Windows Phone 7 Series. The new OS has a requirement for 480 x 800 pixels of screen real estate. We'll start seeing phones running Windows Phone 7 this Summer.
Some smart phones will get a little larger to meet this pixel requirement. Dell's Mini 5 (aka Streak) device has this pixel density on a screen that measures 5 inches diagonally. The screen on HTC's new EVO 4G phone has 480x800 pixels, and measures 4.3 inches diagonally.
Some phones, such as the HTC Touch HD and Nokia N900, use the 480x800 resolution on a 3.5 inch screen today. The result is very sharp text, but the image is a little too small for my taste. I think the 5 inch screen is better for readability. The 4.3 inch screen is a good compromise if you intend to carry the device in your pocket, but still want to view web pages.