The equivalent of Microsoft's Silverlight but for Linux operating systems is available for download as of May 13, 2008, under the label Moonlight. According to the official description of the technology, Moonlight is nothing more than the open source implementation of Silverlight, tailored for UNIX systems. With this latest step in the evolution of Silverlight, Microsoft can finally claim that the technology is truly cross-platform, because ahead of the May 13 public release of Moonlight, support was available exclusively for Windows and Mac OS X operating systems.

Moonlight is a project developed in parallel with Microsoft Silverlight, but not by the Redmond company. In fact, Microsoft partnered with Mono, an open source project backed by Novell, in order to port Silverlight to Linux. At this point in time Moonlight is still in development, and as such comes with the inherent problems associated with any Beta.

"The release comes in two forms: no-media codecs supported, but easy to install. This currently hosts builds for Linux x86 and x86-64 for Firefox. [And] source-code compilation, but you can optionally compile FFMpeg codecs yourself. To do this, download our moon-0.6.tar.bz2. And follow the build instructions", revealed Miguel de Icaza, Novell Vice President for Developer Technologies.

De Icaza noted that Moonlight is designed to integrate seamlessly with both Firefox 2.0 and Firefox 3.0 releases, but that the latest modifications introduced in the development of version 3.0 of Mozilla's open source browser will cause the open source implementation of Silverlight for Linux to malfunction. At this point in time Mono is offering both Moonlight 1.0 and 2.0 versions, adapted to correspond to Microsoft's own Silverlight 1.0 and 2.0 releases.

"Moonlight supports "windowless" mode, a mechanism that allows Silverlight content to blend with other HTML elements on a page. This is only supported by Firefox 3, users of older versions of Firefox might run into Silverlight applications and web sites that do not work correctly as many Silverlight applications depend on this functionality (Flash sites have the same problem with Firefox 2)", de Icaza added.

Novel Moonlight 1.0 and 2.0 Alpha are available for download here.