I have attended the iPhone develop talk held by Apple in 10/14/2008. They popped some NDA blah blah and I'm too tame to break it (I didn't even take any photo, for example), but I should say it is worth the time to take part in. It is not that fantasic, but is OK - I haven't been any conference only talking about tech for years.

Althought it is not all for the tech topics, iPhone platform and the App Store talks didn't take a long time. Besides, I think a lot of people still need it, especially for those who haven't uploaded any apps online yet. Then it comes iPhone UI design, tea break (with both tea and coffee), and at last the iPhone SDK. It would all be nonsense to you if you had read all apples documents before, but I'd figure that it isn't quite possible for most people. And there are some interesting cases being discussed, made it ever more useful for us.

I will write down some pieces tips that seems to be useful to me, such as:

Make a new color theme if you want to make your app special - but not overdo it, of course.
Draw some design concepts on paper. It will actually SAVE you a lot of time in interface builder.
Use Xcode - features like SCM, snapshot and refactor may not be familiar to you, but do try them if you are subversioning, branching and refactoring.
Read apple's documents. And read more. And more.

I am out to take part in another conference (and it sucks) so I didn't take a glance at my notebook, and that's all I can think of for now. Hope it isn't considered breaking the NDA :)