Microsoft officially announced Microsoft Silverlight, a cross-browser, cross-platform plug-in for delivering the next generation of media rich experiences and rich interactive applications for the Web. In other words, Silverlight is the official release name for WPF/E.
For those of you who are wondering where Microsoft came up with the name Silverlight, it is named after David Silverlight. David is the creator of XML Pitstop and Community Credit. He is also a central figure in NonProfitways.com and StupidCubicle.com.
For the full story about how the name came about, check out David's post, but it essentially boils down to Microsoft, and Bill Gates, wanting to recognize David for his contributions to the developer community in some way that is above the normal MVP or ACE Award status.
Congratulations, David! It's not everyday you get a product named after you.