The Open Handset Alliance, the group that manages the Google-developed and -driven Android operating system, said that the entire platform has been released as source code and licensed for liberal use. Open-source licensing typically requires that anyone who distributes versions of a project - whether identical or modified - also make the full code base available. Most developers also contribute any changes they make back into a central repository. The first smartphone using Android shipped 22-Oct-08 from T-Mobile in the United States (see "T-Mobile's Google Phone Promising but Unpolished," 2008-10-20).
The Android Open Source Project chose the Apache 2.0 license, which allows development along both commercial and open tracks, and either track may involve free or for-fee elements. Because Android uses a Linux kernel as its base, however, that part of the project remains under the GPLv2 license, which has broad requirements that prevent closed paths from forming.
The primary difference I can see between the two licenses is that with the Apache 2.0 license, a developer can add to the work and set their own terms regarding distribution and copyright. All the source from the project up to that point still must be noted with licenses.
Open-source licenses vary widely, with many allowing commercial resale of derived software, and some requiring the release of any code that a developer or firm has modified and then incorporated in a distributed release. These licenses typically affirm intellectual property rights, and assign a chain of rights as the work develops. Apple, for instance, uses FreeBSD for much of the core of Mac OS X; the associated license requires notices of copyright to be attached, but has no mandate to keep development open or contributed back to the root.
The use of an Apache 2.0 license is critical for Android because handset makers and others may want to develop custom versions of Android that their competitors can't simply copy from the code base and use. On the other hand, in order to keep the operating system in sync, most proprietary changes will likely be overlays and modules; otherwise, it would become an unmanageable task to fold in improvements while maintaining copyright separation.
Reports indicate that Android will likely be used for a variety of handhelds, tablets, and mobile gadgets, as well as a replacement for existing "embedded" operating systems used for devices that aren't computers, like cable set-top boxes. The richness and newness of the platform apparently makes it more compelling than many embedded offerings currently on the market.