Maintenance is often done only by the open source vendor -- they do not accept code contributions from non-employees. This is not a universal rule, of course. Open source projects remain viable by following the desires of the product community; to reiterate a point, constant and transparent communication between vendor and community is critical. There is no guarantee that today's open source project will be available in five years. The same may be said, of course, for commercial products. The difference is that, should a commercial product be withdrawn from the market, its users are stranded. The source code for an open source product is always available, which allows the user community to take up the code base should the vendor withdraw its support for it.
This was first published in January 2006