Google Open Source Pledge
Open Source is the way to innovate and users using it should have complete freedom. Google has came forward to declare couple of its patents on Map Reduce under Open Patent Non-Assertion Pledge (OPN Pledge). There are multiple variants of open source license and using that means the product is completely free. Why OPN Pledge is required?
Free Sofware Foundation (FSF) and OSI has approved many licenses and most of them are related to code and coypright licenses. They are not copyleft. These licenses do have some obligations. In Open Source world, you are not necessarly to contribute code. You could contribute idea, which others could develop.
The OPN Pledge is oriented to open source software to which Google has contributed little or no code, or has not otherwise incurred any patent license obligations under patents it owns. The OPN allows us to do more than conventional patent rights transfer mechanisms around free or open software would allow.
Google has come forward and declared its 10 Map Reduce patents under OPN Pledge. In these areas, it might have contributed less in terms of code but it still holds the idea. They now declared that they own these patents or ideas but they don't sue others who use it.
This is great as this will allow others to come forward to pledge their patents. Open Source is the way to innvoate and it requires freedom. You pledge your idea and others may implement it. Still the world knows, you created it.
Google OPN Plege
Google Open Source Blogspot