Microsoft has been working on Eclipse Tools for Silverlight since October of 2008 and is now at the 1.0 release.

"The Eclipse Tools for Silverlight (Eclipse4SL) plug-in is an open source, cross-platform plug-in for the Eclipse development environment that enables Eclipse developers to build Silverlight Rich Internet Applications (RIAs)," Microsoft explains in a blog post.

That's right, it's an open source Microsoft effort for Silverlight and no it's not Novell's Mono. The Novell Mono effort is an open source effort to provide Silverlight to Linux users, but with all of Microsoft's own open source Silverlight efforts, I'm beginning to wonder about its future relevance. After all, if Microsoft itself is already doing open source releases of Silverlight related tools why is there a need for another (similar) effort?

The other important thing to remember about today's Microsoft Eclipse announcements is the practical reality for many Eclipse based IDE developers. For years I've been told (and seen for myself) Eclipse based IDEs (from IBM Rational and others) running on Windows desktops.

So while Eclipse itself is open source, many of its users have long been using Windows as their desktop development environment anyways. As such it only makes sense to have a solid degree of Windows interoperability.

"We are always working hard to find new ways to provide more choice and opportunity for developers in our ongoing journey to foster interoperability between Microsoft products and other technologies," Microsoft's Vijay Rajagopalan wrote in a blog post. "We are hoping that today's announcements give developers the additional choices and opportunities they're looking for, and that they amount to yet another reason why choosing Microsoft platforms means keeping all the options open."