Microsoft has released 20,000 lines of codes of device drivers for the Linux community. Microsoft official press release confirms that they will be releasing the device driver codes under GNU General Public License (GPL) V2.
This is a very generous move by the Microsoft but yet, this is a proxy win situation for Microsoft.
Simply because this will enhance the support for Linux when it is virtualized on Windows Server 2008 Hyper-V or Windows Server 2008 R2 Hyper-V.