The Wine mailing list has 5 patches which when applied to the Wine 1.5.17 release should allow Silverlight v4 to work under Firefox for Windows to access Netflix. While these patches do not claim to provide a fully functional Silverlight, being able to support use of Netflix seems like a huge step forward in terms of features that Linux adopters frequently request.
More details available at:
http://www.iheartubuntu.com/2012/11/netflix-on-ubuntu-is-here.html