In the past Microsoft has been hostile to the open source movement. But At OSCON, Microsoft announced their sponsorship of "The Apache Software Foundation", joining Google and Yahoo! at Platinum level. Microsoft donated US $100k (minimum requirement, MS did not disclose how much money it had contributed) to Apache foundation. This sponsorship will enable the ASF to pay administrators and other support staff so that ASF developers can focus on writing great software.
According to Sam Ramji:
It is not a move away from IIS as Microsoft’s strategic web server technology. We have invested significantly in refactoring and adding new, state-of-the-art features to IIS, including support for PHP. We will continue to invest in IIS for the long term and are currently under way with development of IIS 8.
It is a strong endorsement of The Apache Way, and opens a new chapter in our relationship with the ASF. We have worked with Apache POI, Apache Axis2, Jakarta, and other projects in the last year, and we will continue our technical support and interoperability testing work for this open source software.