Microsoft's Shared Source Initiative and the Microsoft Public License (Ms-PL) -- the permissive MIT/X11 resp. BSD-like OSS license from Redmond

Also Microsoft has discovered the advantages of OSS driven software development and released an own OSI approved OSS license called Ms-PL which is also used for MSDN Code Gallery. Unlike the GPL, the Ms-PL is a permissive software license that allows make closed source derivatives from existing project licensed under this license. Therefore the Ms-PL is comparable to the MIT/X11 or the BSD license.

There is a nice overview about software licenses offered by Microsoft's Shared Source Initiative which currently consists out of three licenses. Aside from the Ms-Pl there is also the Ms-RL and the Microsoft Reference License. Thereby the Ms-RL is Microsoft's most restrictive shared source license that allows licensees to view source code in order to gain a deeper understanding of the inner workings of a given technology. This license is primarily used for development libraries that behavior under certain circumstance cannot be explained by natural language well. The Microsoft Reciprocal License is the effort to simplify the legal treatment of code in collaborative development projects where existing Ms-RL have to be combined with licensee's own code. This license model was designed to facilitate the commercial as well as non-commercial modification and redistribution of licensed software.

So there is not only the EULA concept in Microsoft's copyright world.