Netflix announced the new movie player based on Microsoft Silverlight a week ago. Now the player that supports both Apple OS X and Microsoft Windows can be used by every Netflix subscriber. The new Netflix movie streaming software is still in beta.
Netflix cautions that there will still be bugs. The bigger issue for now is that not all movies are available to watch with Silverlight. If you opt-in to use the new Sliverlight player you need to use that on all your Windows PCs.
If you need access to all Netflix digital offerings you should stay put. If you are only using an Apple Mac this new player is your only way to watch Netflix anyway.
More details on the Netflix blog.