One thing about Steve Jobs, who made the announcement yesterday.
Apple doesn't announce stuff unless it is well underway. That means their code jocks are almost assuredly working on the SDK now.
And that anticipation you feel in the air is from third-party developers with lots of ideas about third-party iPhone programs- and fingers crossed that the SDK will allow this.
My question to you current, will-be and might-be iPhone users:
What applications, programs, widgets, etc. would you like to see developed by means of this SDK?
I'll take your Comments below.