Microsoft’s Scott Guthrie has announced the final release of Silverlight 2.0, its browser plug-in which includes a cross-platform implementation of the .NET runtime as well as a multimedia rendering engine. It will be available for download tomorrow.

Not really a surprise, but nonetheless a significant moment for Microsoft. I have been watching the project closely since it was first announced at PDC 2005 as Windows Presentation Foundation Everywhere. I am particularly interested in the cross-platform aspect. When .NET was first released in 2001, as Microsoft’s answer to Java after falling out with Sun, it had obvious cross-platform potential, yet the company held back form any commercial implementation outside Windows. Miguel de Icaza took independent action to create an unofficial open source Linux implementation, that also runs on Mac and Windows, called Mono. Microsoft was initially wary of Mono, but in my view the company had more to gain than to lose by supporting it. That now appears to be recognized, with Microsoft working formally with Mono to support Moonlight, Silverlight on Linux, and to provide it with multimedia codecs.

Microsoft has also announced Eclipse tools for Silverlight, in partnership with Soyatec, the idea being to enable Java developers to develop for the Silverlight client within Eclipse.

One clarification: although the press release says “This includes support for Mac, Windows and Linux”, the Mac support for Silverlight 2.0 is Intel Mac only, and the Linux version lacks multimedia support and the 2.0 version is described as “Experimental”; it is a long way from full release. Although Microsoft is now working with Mono, cross-platform currently means Windows and Intel Mac, though this does account for a large proportion of active Web users.

Press release is here.