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With the release to the Web of Silverlight 1.0, the cool new cross-browser, cross-platform technology for developing rich media experiences and interactive applications, Microsoft also released Expression Encoder 1.0 (formerly Expression Media Encoder), a tool for encoding, enhancing, and publishing rich media content to Silverlight. Expression Encoder is an application included with the Windows version of Expression Media that enables you to convert and compress multiple video formats to SMPTE standard VC-1 video for mobile, Web, and HD video scenarios.
sounds good
linux AND mac support? neat.