Adobe announced the Adobe Media Player and Microsoft sounds-off Silverlight as the future of online video entertainment.

Microsoft Silverlight is a new cross-browser, cross-platform plug-in for delivering the next generation of media experiences and rich interactive applications (RIAs) for the Web.
Silverlight uses Windows Media Video (WMV) and deliver digital rights management support, built on the recently announced Microsoft PlayReady content access technology.
Microsoft signed the following partners to support Sliverlight: Akamai Technologies Inc., Brightcove Inc., Eyeblaster Inc., Limelight Networks, Major League Baseball and Netflix Inc.
Akamai also shows-up as a supporter of the Adobe Media Player. So there is no exclusivity to these partnerships.

Microsoft will also release the beta for Silverlight during the Mix07 conference.
Via Microsoft Silverlight press-release.