The original version of Interactive Media Manager was released last April, and the next version, now updated to include SIlverlight, was announced at the National Associate of Broadcasters Conference on April 11-17. 

Review the blog entry about this at http://blogs.msdn.com/sharepoint/archive/2008/03/31/microsoft-interactive-media-manager-a-digital-asset-management-solution-built-on-top-of-moss-2007.aspx

See the Microsoft page about the newly released Media and Entertainment solution at https://www.microsoft.com/resources/mediaandentertainment/solutions_imm.mspx

For more information on Silverlight: http://www.microsoft.com/silverlight