Microsoft has made its second release under the General Public License in two days with software for the open-source online learning system Moodle.

Microsoft released the Live Services Plug-in for Moodle under the GPLv2, a move outlined in a blog post by Peter Galli, a community manager for Microsoft's Platform Strategy Group.

The plug-in adds Microsoft's Live@edu services such as e-mail, calendar, instant messaging and search directly into the Moodle user experience and makes them available via single sign-on, he wrote.

Moodle is a free open-source course management system that teachers use to create online learning Web sites for their classes, and it has about 30 million users in 207 countries, according to Galli.

The Microsoft Live Services Plug-in for Moodle is the first of what will be a set of software releases for the education community that Microsoft will make available for download online via its Education Labs Web site, the company said through its public relations firm.

Until Monday Microsoft had not released anything under the GPL -- a popular open-source license it's criticized in the past -- but now the company seems to be embracing it.

While Tuesday's release certainly is not as significant as Monday's unprecedented release of 20,000 lines of code to the Linux kernel, including drivers for virtualizing the open-source OS on Microsoft's Hyper-V software, it is indicative of a trend the company started about two years ago to work more closely with the open-source community. This trend is in part a nod to the growing heterogeneity of IT environments, in which Linux and proprietary technologies like Microsoft software are increasingly being deployed side by side.

But even while on one hand Microsoft is working more closely with the community, on the other it continues to strike patent deals with open-source companies to collect royalties for patents it says it holds on technologies found in Linux and other open-source software. In general, Microsoft continues to uphold its proprietary intellectual property licensing strategy -- the opposite of the philosophy behind open source.

The most recent patent deal came last week with the Japanese company Melco Holdings -- the parent company of Buffalo Inc. and

Buffalo Group. Microsoft and Melco agreed to provide Melco customers patent coverage for their use of Buffalo-branded network-attached storage devices and routers running Linux. In exchange, Melco will pay royalties to Microsoft.