Expression Web is part of a suite of tools called Microsoft Expression, which also includes Expression Graphic (for graphic design) and Expression Interactive (for application design). Expression Web is a standards-based editor that supports XHTML, XML, XSLT, HTML, and accessibility standards. PCMag.com gives this beta version four out of five stars and thinks that this software will set the standard when the final version is available. Definitely something to watch.
The beta version is available at no cost until March 31, 2007. If you have installed beta version 1 or 2 of Microsoft Office 2007, you must uninstall these before installing Microsoft Web.