Open Source iPhone Software

Yes!! Open source exists on the iPhone.
While the phone OS may be closed, you can still run free and open software. Here's a list of the best open source on the iPhone. Updated often as new apps come out!

Publishing

• Download from iTunes

  WordPress

  WordPress is the cleanest and most popular blogging service. This app lets you create and edit content on your blog with support for offline use.
  

Reference

• Download from iTunes

  wikiHow

  wikiHow is a beautiful and simple how-to wiki so you have a user's manual for everything at your fingertips.
  

Music

• Download from iTunes

  Noise

  Grid is an open source additive synthesis system ideal for rhythmic, melodic, or textural applications.
  

Games

• Download from iTunes

  Wolfenstein 3D Classic

  Wolfenstein is one of the original First Person Shooter games.
  
• Download from iTunes

  Doom Classic

  Doom Classic. Nuff Said.
  
• Download from iTunes

  Star3map

  Star3map is an augmented reality star and planet charting application for the iPhone 3Gs
  

Entertainment

• Download from iTunes

  Now Playing

  With Now Playing you can read movie reviews, locate theaters and show times, even purchase tickets.
  

Utilities

• Download from iTunes

  Funambol

  Funambol delivers over-the-air backup and syncronization of your iPhone contacts.
  

iPhone Hacks

We know these aren't up to date. Update Coming Soon!

• Download Page

  ZiPhone Jailbreak

  A Jailbreak app.
• Download Page

  QuickPwn

  The quickest jailbreaking solution!
• Download Page

  Installer.app

  Use Installer.app to install any third-party software on a jailbroken iPhone.
  
• Info Page

  Linux on iPhone

  
  

Developers

• Info Page

  Something Facebook-y

  The best free anti-virus program.
• Download Page

  iPhoney

  iPhoney gives you a pixel-accurate web browsing environment that you can use while developing web sites for iPhone.
  
• Download Page

  TouchCode

  TouchCode is an iPhone Open Source umbrella project encompassing a number of technologies not included in the Apple Cocoa environment.
  
• Info Page

  OpenClip

  OpenClip is a non-profit, open-source, community-effort project, which promotes a framework for the iPhone that allows users to copy / paste between participating applications.