Xfce 4.2.0 can be downloaded here.
Xfce 4.2.0 includes new applications like a session manager and an application finder, a new and beautiful icon theme, support for bleeding-edge features (like the X.org Composite extension), usability and performance improvements, better support for multihead desktops, new and updated translations, additional themes, and various other improvements over the previous stable releases. See this page for a complete list of changes between Xfce 4.0 and Xfce 4.2.
Furthermore, Xfce 4.2 is the first desktop environment to ship with an easy-to-use and platform-independent graphical installation wizard, which takes care of compiling and installing Xfce on your system. Visit the os-cillation installers website for download links and instructions.
A short trailer that introduces Xfce 4.2.0 is available in high- and low-bandwidth versions here.