The Open Source Census, a project aiming to tally usage data on open source software in business and use that tally as a way to promote more corporate use of open source software, just signed up a surprising new sponsor: Microsoft.

"Our customers, partners and developers are working in increasingly heterogeneous environments, and our participation in industry projects like The Open Source Census are relevant for the ecosystem in which we participate," Sam Ramji, Microsoft's senior director for platform strategy, said in a statement.

Microsoft's membership in a group committed to making the use of open source software more prevalent in the enterprise may sound counter-intuitive, but that thought is only half right. While Microsoft competes with open source software in many specific product areas -- including operating systems, Web servers, Web browsers and CRM -- the company has also increasingly been reaching out to the open source community.

The community outreach shouldn't be perceived as foreshadowing that Microsoft will soon open source much of its own software; Microsoft CEO Steve Ballmer called the open source model "inconsistent with shareholder value" just last year. However, Microsoft does want to see Windows as a growth platform for open source software, and usage data could be used to help figure out where Microsoft should put more emphasis on interoperability.

"With the growth of open source development running on Windows -- including major communities like Apache, Firefox, and Eclipse; community development projects on Sourceforge and Codeplex; and partnerships with commercial open source vendors like JBoss, Zend, SugarCRM, and SpikeSource -- the business opportunities and the choices available to partners and customers on the Windows platform have never been greater," Ramji said in the statement.

Of course, the sponsorship can't be entirely altruistic. Hard data on the shape of open source software usage is difficult to come by since it can often be downloaded, shared and used at will. With more data, Microsoft would undoubtedly be able to better understand its open source competitors and where exactly their weaknesses lie.

The Open Source Census was started in April by open source management company OpenLogic and relies on anonymous scans of computers to count open source installations with software called OSS Discovery. So far, 228,117 open source installations have been found from all company sizes and industries, with the Firefox Web browser at the top of the list of most popular open source software.

Companies and individuals who take part in the Open Source Census gain access to detailed reports on their own open source use and comparisons with similar companies, though less specific reports are available to the general public.