bluewoki is a simple walkie-talkie over Bluetooth and wifi for devices running iOS 4.0+. It allows iPhone and iPod Touch devices to connect to each other via Bluetooth or a wifi network to exchange vocal messages. When using Bluetooth, the devices must be close enough to each other so that they can connect.
The application is available at the App Store.
The source code is released under a liberal BSD license. The project uses and includes the AsyncSocket library, which is in the public domain.
Xcode 4.1 is required to open the project.
This question has already been raised in the case of Tux Raider World Challenge and I will simply quote one of its FAQ entries:
Tux Rider is an Open Source software that complies to the GPLv2. Hence the source code is made available to all clients. Yet, the GPLv2 doesn't says that the author cannot be rewarded for his work. In fact, there is a widely spread misunderstanding that says that Open Source equals free of charge. The free software foundation clearly explains: “Free software is a matter of liberty, not price. To understand the concept, you should think of free as in free speech, not as in free beer.” — The Free Software Definition (GNU - FSF)
Read this amazing article by Zed Shaw. I completely agree with his views on licensing.