I just got done reading the NYT article For iPhone, the 'New' Is Relative and here is an excerpt I like about some of the apps coming for it:
Apple has demonstrated 16 of these programs, including an instant message program, an eBay auction tracker, medical references and a touch-sensitive musical keyboard; the best of them exploit the iPhone's orientation sensor, wireless technologies and other high-tech components.
One coming program, called iCall, will give you free phone calls when you're in a Wi-Fi hot spot. Another, called G-Park, exploits G.P.S. to help you find where you parked. Yet another, Urbanspoon, is "a cross between a magic eight ball and a slot machine:" you shake the phone, and it randomly displays the name of a good restaurant nearby, using the iPhone's G.P.S. and motion sensor.
You can also expect to see a time and expense tracker, home-automation remote control, voice recorder, Etch-a-Sketch, a recipe box, tip calculator, currency converter, e-book reader and so on.
Above all, the iPhone is about to become a dazzling hand-held game machine. The games revealed so far feature smooth 3-D graphics and tilt control; in one driving simulator, you turn the iPhone itself like a steering wheel, and your 3-D car on the screen banks accordingly. Other games exploit the multitouch screen, so you and a buddy can sit at opposite ends of the screen and fire at each other.