iPhone Programming for newbies

Objective-C is a reflective, object-oriented programming language, which adds Smalltalk-style messaging to the C programming language. Today it is used primarily on Apple's Mac OS X and iPhone OS: two environments based on, although not compliant with, the OpenStep standard. For all of the "classic" programmers that are starting now, you should from now that with Objective-C, you will need to take care of the objects from the creation time up to the destruction time.
iPhone programming environment doesn't offer so far Garbage Collector implementation, so it's very delicate programming style.

XCode

Xcode is a suite of tools for developing software on Mac OS X, developed by Apple.Xcode includes all the tools you need to create, debug, and optimize your applications. At the heart of the Xcode tools package is the Xcode IDE, a graphical workbench that tightly integrates a professional text editor, a robust build system, a debugger, and the powerful GCC compiler capable of targeting Intel and PowerPC regardless of host platform.

Instruments

Instruments is a brand-new, timeline-based performance visualization tool that gives you the ability to see how your application works like you've never been able to do before. It lets you watch CPU, disk I/O, memory usage, garbage collection, events, and more in the form of graphs tied to time. Basically you will work with Instruments all the time during developing your application in order to eliminate "memory leaks" and also inspect the CPU usage to avoid "battery killing".

Interface Builder

Interface builder is the intuitive, easy-to-use tool for creating and editing user interface resources files (nib files). These files represent a set of interface objects and their relationships, as well as their connections to your application's logic.
.nibformat = NeXT Interface Builder. This is an archive-like file, stored in XML format for all the objects you are creating in Interface Builder. I won't go too deep into this because my style of work doesn't include Interface Builder at all.
Why is that? Well, even if this is a feature of the iPhone SDK and not an option, the main reason for disowning Interface Builder is that IT DOESN'T GENERATE CODE for the objects you are creating there. It was like a hit straight to my face when I first discovered that, so I'm thinking that sharing that with you will spare you of several time to clear up this dilemma.

iPhone Simulator

The iPhone simulation environment lets you build and run your iPhone application on your computer. You are building an application and you didn't get a device yet? Not a problem, iPhone Simulator will do the business. Just like using a real device, iPhone simulator has support for: tab, double tap, touch and hold, swipe, flick, drag, pinch and many others. Still, you must be very careful in getting used with the simulator because the real experience in iPhone Programming is with the iPhone Device.
First of all, iPhone simulator supports few libraries which are not available in iPhone OS, but are available in your Mac OS. More than that, the device is constrained by hardware limits (for example, only 400 or 600 Mhzsingle core processor, not even close to what your Desktop might have) and you should really consider that in projecting and developing your applications.

The "Experience"

The first few steps you definitely want to do before starting is to search over the Internet for some advices on how to start, where you can find some beginner tutorials, which are the most evolved communities of iPhone Programmers. First of all, create a developer account (which is free). On the main page of the developer account you will find some great starting Videos and also Starting Documents. If the lecture will become boring, you can just start with the Videos for the beginning.
Other great sections are: Sample Code: where you can download some Apple Samples of applications which will definitely help you a lot.

Beside what Apple is offering, I am recommending also iPhone Dev SDK Forum which is a great community with starting developers and also experienced ones, which are very communicative and kind to give us a helping hand.
The other great resource I've found and it seemed incredibly useful for me was the CS193 iPhone Programming course of Standford, I definitely recommend you those videos. They really helped me to better understand and follow some great principles of iPhone programming.