Microsoft’s Expression products, such as Expression Blend, Expression Web, Expression Design, and Expression Encoder, are commercial software development tools used for developing websites and applications. The Expression brand was introduced in 2005, and the first Expression Studio package (which consolidates the products into a suite) was released in 2007. The most recent Expression Studio (version 4) was released in 2010, and this looks to be the last Expression Studio that Microsoft will put out.
On the Expression website, Microsoft has announced its plans for the products. For one, Expression Studio 4 Ultimate and Expression Studio 4 Web Professional are no longer available for sale. If you’ve one of these, all components within will still be supported through their support lifecycle. Secondly, Expression Design 4 and Expression Web 4 are now available for download at no charge. Thirdly, Expression Encoder 4 Pro will be available for purchase through 2013 (the non-Pro version is available as a free download).
Lastly, as “part of a consolidated designer/developer offering”, Blend will continue to ship as a standalone tool with Visual Studio 2012. In addition, a Blend + SketchFlow Preview for Visual Studio 2012 that supports WPF/Silverlight editing and SketchFlow is now available for download.
Source: Microsoft Expression website.