Previewed at WWDC, launching in the fall.
Greg Joswiak on the iPhone SDK, iPod
The article covers Apple's marketing and research focus over the years, and does reiterate that Apple will likely be using a digital-signature approach to the upcoming iPhone software developer kit.
One of the things Steve talked about in his open letter is something Nokia's doing, which is requiring a digital signature. That way if there's something wrong with an application, you have a way to track it back to where it came from.
Joswiak also claims that one of the main advantages Apple has over their competitors is looking ahead to the future:
Our competitors tend to put the cross hairs on where we are now, and by the time they come up with a product that tries to match where we are now, were beyond them. Were one or two generations beyond, moving faster than they are.