The good folks at NCMIR - National Center for Microscopy and Imaging Research have released a port of the Scalable Adaptive Graphical Environment (SAGE) for Windows for download. This allows you to create large tiled displays - we even had one running at our SC07 booth.
SAGE is a graphics streaming architecture, originally developed by the Electronic Visualization Laboratory at the University of Illinois at Chicago (http://www.evl.uic.edu/cavern/sage/), for supporting high-resolution, scalable and collaborative scientific visualization environments. It is primarily designed to be run as a thin middleware on a high bandwidth-enabled, cluster-driven tile displays. It allows users to treat the high-resolution distributed displays as one contiguous desktop where users can move/resize application windows. SAGE is network centric and the applications running on these displays need not run locally. The applications can be run on remote machines or clusters, and they can stream their pixel frame buffers to SAGE-enabled tile displays.