http://icodeblog.com/ - An excellent web site for learning iPhone programming.  Includes many detailed examples which can be easily followed by the reader.

http://www.appsamuck.com/ - Offers 31 iPhone source code examples in various iPhone aspects.

http://www.iphonedevcentral.org - Has many good iPhone SDK development tutorials.

Stanford University Video class lectures  - Stanford University offer a course on iPhone programming. Now they added Video class lectures, and slides in PDF format.

Stanford University - Stanford University offer a course on iPhone programming. You can download all lecture slides, and excursuses.

http://cocoaheads.byu.edu - Host many Mac OS-X code examples which you can learn from, and implement some of it on the iPhone as well.

http://developer.apple.com - Apple Dev Center is a great place to start your iPhone exploration.