How To: Install Apps on Your iPhone Easily, No Hacking Skills Required

IMPORTANT: If you are looking how to install apps on your iPhone or iPod touch, these instructions are no longer valid. Follow this link for new instructions.
If you wanted to install third-party native software in your iPhone but you didn't had the necessary technical knowledge or courage, the newly updated iPhone Installer.app will make it so easy that it will be very hard to resist. We have tried it in Mac OS X and, as you will see in the tutorial after the jump, it works perfectly -including the installation of applications over Wi-Fi and EDGE. [Updated 4:45PM EST]
Once you download the application from the link below, you only have to connect your iPhone to your Mac (PowerPC and Intel will work, we have tried both) and run the script from the Mac OS X Terminal. Doing this is quite simple:
Preparation
• Download the installation file to your desktop.
• Connect your iPhone to your computer using the provided cable.
• Deactivate the iPhone automatic synchronization in iTunes before proceeding and close iTunes.
Steps
• Go to Utilities in your Applications folder and find Terminal.
• Double-click on Terminal.
• In the Terminal, go to the folder that contains the application installation script. You can easily do this by typing cd in the command line, then space, then dragging the iPhoneInstaller folder into the Terminal Window. This will automatically paste the path in the Terminal. If you saved the iPhoneInstaller folder to your desktop like we told you, it will look something like this:

cd /Users/your_user_name/Desktop/iPhoneInstaller/

Hit the return key to change to that folder.
• Now run the script, which is called get_installer.sh, by typing the following:

./get_installer.sh

• The script will now run, asking you what version of firmware do you have. If you updated your iPhone, you will have 1.0.1. If not, select 1.0 by typing the option.
• The script will automatically download the necessary restore file from the Apple servers.
• When it's done, it will prompt you to hold the home button (with the square) and the power button (on the top) at the same time (hold first the home, then hold the power).
• When the message "Connect to iTunes" appear in your iPhone, release the buttons and let the thing do its magic.
The iPhone will restart and you will find a new icon in your home screen:

You can disconnect the iPhone now. If you want, enable automatic sync in iTunes before disconnecting.
Now you will be able to install applications from the Installer. This is extremely simple. Just open the Installer application and select the software you want to install.
One more thing: before installing any new applications, you may want to update the Installer itself by clicking on the "Update" tab.
Installing applications
When you start Installer you will see only a handfull of applications. They are Nullriver's apps, which include a BSD Subsystem and MobileTerminal. To access all third-party software available, do the following:
• Launch Installer on your iPhone. It will connect to the Internet and register the available packages.
• Click on Community Resources package inside the Install tab.
• You will see the detail. Click on the Install button.
• After installing, you will see all the third-party applications currently available for iPhone.
• Click on any of them, hit the Install button and enjoy.
Extremely smooth and easy. Our congratulations to the Nullriver people for a truly great piece of software.
UPDATE: As someone points out in the Digg comments, the other thing you should do after updating the Installer and before start installing applications is to install the Launcher application. The reason: the iPhone springboard (the home screen) won't scroll, so if you install many applications, you won't be able to access some of them. The Launcher gives you a way to access all non-Apple apps from a scrollable list.