There’s an underground app store on the iPhone and it’s only available to "jailbreakers." People that decide to hack their iPhones do it for a variety of reasons, but being able to run applications in the background on their phone is one of the main ones.

With recent talk about jailbreaking the iPhone 3GS, some people might still be wondering what it is and how it could benefit them. To help those new to the iPhone and for those iPhone owners without a super-nerd friend to pummel with questions about the Pwnage tools and the iPhone-Dev Team, we answer a few basic questions about jailbreaking the greatest device ever.  

What is Jailbreaking?

The first jailbreak was released two weeks after the iPhone's initial release in June of 2007 and allowed users to customize their ringtones. A few months later, jailbreak users could install third-party applications on the iPhone. Jailbreaking is not the same as unlocking, which allows you to place a different SIM card in your iPhone to use on other GSM carriers.

The basic ideas of jailbreaking remains the same. The jailbreaking process involves tweaking the Apple firmware and opening doors to third-party, non-Apple approved applications and tweaking the user interface (i.e. adding themes, changing icons, colors, etc.). Once the jailbreaking software on your Mac has altered the iPhone firmware, it will install the custom firmware onto your device.

This process is called jailbreaking, because you're freeing your iPhone/iPod touch from the bonds of Apple, which picks and chooses what its users can do with their devices. Also it sounds kinda cool. Like you're a low-level criminal. 

Some Pros/Cons of Jailbreaking

Background Processes

If you want the ability to run an app that isn't the current app in the foreground on your iPhone, jailbreaking can do that for you. For example, if you want to run a chat application in the background and still receive IMs even though you're checking the weather in another application. This is possible with background processes and without push notifications. Another example is GPS apps. They have to be running in the foreground to work on your regular non-hacked iPhone. If they're  running in the background on a hacked iPhone, you can check your email, take a call, or switch up your music playlist and the GPS app will continue to track your path. 

The downside to applications running in the background is that you will find that your battery drains much quicker and the iPhone will slow down once you have a few processes running along side that of the currently open application.

Apple Updates

A major con that comes to mind with the jailbreaking process is that when Apple updates the iPhone/iPod touch firmware/OS, the new iPhone software overrides the hacked software you have on your iPhone. After each Apple software update, you usually have to wait until the iPhone Dev Team releases an updated jailbreaking tool to update to the latest and greatest features implemented by Apple. This wait can be anywhere from a few hours to a few weeks depending on the update from Apple.  

This means you'll be constantly jailbreaking your iPhone in order to keep the features you covet on your device.

Pushed Away

Push Notifications, the little messages you might get on a non-jailbroken iPhone when you get an IM in Beejive or AIM, don't always work on jailbroken devices for some people. The fact that you can run apps in the background makes this con easier to swallow. 

Breaking the Law?

The legal issues surrounding jailbreaking is also a big deal. Since you are hacking around with Apple’s software, it's a bit of a "gray area" surrounding the DMCA (Digital Millennium Copyright Act), which tries to keep people from, among other things, reverse engineering copyrighted software.

Jailbreaking does allow you to have some pretty nifty and free options added to your iPhone/iPod touch, but Apple is definitely adamant about fighting jailbreakers. For instance, if you take your iPhone in for repair at an Apple Store or through AppleCare, it would probably be in your best interest to restore your device. Apple has been known to refuse service to iPhone/iPod touch owners who have jailbroken their devices.

The Jailbreaking Process

The ability to jailbreak your iPhone is made possible by groups like the iPhone Dev Team. They create the tools needed to unlock your iPhone. 

The tools utilize the Apple approved firmware as a base to create a custom firmware based upon what you want your iPhone to do. The resulting .IPSW file is then loaded onto your iPhone via iTunes. 

There are a few different pieces of software that allow you to do this, most notably the iPhone Dev Team’s PwnageTool that runs on the Mac and allows you to compile firmware for iPhone, iPhone 3G/3GS, and iPod touch 1st/2nd gen. There’s also an application that runs on Mac, Windows, and Linux called "redsn0w" that is made by the iPhone Dev Team and the Chronic Dev Team.

Getting Applications for your Jailbroken Device

The App Store allows you install applications on your iPhone/iPod touch with relative ease. If you plan on jailbreaking your iPhone but you're concerned you'll lose the App Store. Don't worry, the App Store works fine with jailbroken iPhones. In fact, with a jailbroken iPhone, you'll be opening yourself up to a world of new apps that don't jive with Apple's rules and regulations. 

Installer applications come with your newly jailbroken device. These applications are Cydia, Icy, and the old and rarely used, Installer.app. This means that you can have the best of both worlds: the Apple controlled App Store, and the open, free applications of the app installers.

Many applications that have disappeared from the App Store for content violations have reappeared in Cydia or Icy. Most notably, many Google Voice applications pulled from the App Store you can now download from Cydia or Icy. Since Apple doesn't control the content in this store, it’s an "anything goes" model of application development, which many open-source fans like.

Of course that lack of control does mean that you could download an app that could crash your iPhone or not work at all. Patience can be key when trying to find a app that accomplishes a task or adds a feature. We found ourselves downloading three to four apps that promised to do the same thing then uninstalling the two to three that just crashed upon launch or froze the iPhone. 

Jailbreaking your iPhone can be a fun exercise or way to enhance your favorite piece of technology. We definitely wouldn't recommend jailbreaking to our less techie friends who just want a working device without the hassle. We would have to recommend that you not jailbreak your main device since you can occasionally run into devastating problems during the installation or regular operation unless your comfortable with that possibility. But, if you're an early adopter with more than one iPhone or iPod touch on hand, jailbreaking might be an intriguing project. 

Good luck.