According to their ‘Sponsors page’ the open source census is sponsored by Microsoft. The fact that the open source census is for monitoring how much open source software is being used in enterprises makes it somewhat strange, but then after I thought about it again I figured Microsoft just needed to get rid of some money and knows that open source is a good cause.

After actually putting some thought into it I determined that they did it because they would gain something from it, my guess is that the something is the % of servers running Windows.

Another thought is that Microsoft felt guilty after trying to sue open source for infringing on over 200 patents, even thought the patented things were almost all in open source before they were in Windows. Go figure.