Service Pack 2 (SP2) for Expression Encoder 4 was released today, and comes with some great updates. For example, SP2 adds the ability to do GPU encoding with Intel Sandy Bridge processors, and there are new multi-channel audio options including AAC and SRS support. For live scenarios, you can now control IIS Smooth Streaming publishing points from Expression Encoder. There have also been improvements in screen capture encoding, the built-in player templates, and new SDK samples to help you get started faster with building encoding applications.

There are over 300 improvements and fixes in SP2.  Get more detailed information on the Expression Encoder team blog.