Microsoft sharing code?

Rather unusual for Microsoft to share its source code, I think:

Microsoft Corp. announced this week it is making the programming code for its Office 2003 software suite available to government agencies around the globe, a move partly aimed at allowing them to inspect the product for flaws and security problems.

Though Microsoft usually guards such software coding tightly, the step is an extension of an initiative the company began in January 2003 giving about 60 governments access to the inner workings of the Windows operating system. This is the first time the software giant has shared the source code for Office, which includes the Word text processing, Excel spreadsheet, and PowerPoint presentation programs.

Apparently Microsoft has shared some source code before. I'm surprised that this source code hasn't found its way onto the Internet. Or maybe it has, I suppose I don't follow this stuff that closely.