We have already seen how Microsoft is ramming its 18,000 patents into all Android device manufactures and making them pay for technologies that Microsoft does not deal with even remotely. Microsoft is nowhere in the Android game and this is a questionable action from Microsoft. Owning a lobby of patents to raise hue and cry on every other Android related technology is not really an ethical business practice. If you want to know how exactly Microsoft is earning more from Android than its own Windows Phone 7 platform, read this coverage by Joel Fernandes.
The world of software patents is getting ugly and the competition is extremely high. In such a world, it is extremely important to have a fair understanding of the technologies you are dealing with and the patent infringement it can cause. Generally, Open Source projects are not claimed against patent infringements because they are community efforts mostly and because they do not have the funding to pay hefty sums. However, prevention is always better than cure.
The Debian project has created an FAQ with some heavy legal aid that can give people an idea of patent liabilities pertaining to Community Distribution of Free and Open Source Software. It starts with the very basics of patents and explains the difference between patents and copyrights. Then, it goes on to explain infringements and the risk of patents to FOSS community projects and limitations of geographical boundaries on patents. If you are a developer working on a community project, you should absolutely know the risks and liabilities involved and this FAQ can offer good help to get started.