I recently came across this paper from Spain published in IJSP (October 2006) comparing 31 commercially available slide systems in pathology.
The paper can be downloaded here. A complete list of the vendors and their websites is available in the paper.
Critical comparison of 31 commercially available digital slide systems in pathology.
Rojo MG, Garcia GB, Mateos CP, Garcia JG, Vicente MC.
Advances in new technologies for complete slide digitization in pathology have allowed the appearance of a wide spectrum of technologic solutions for whole-slide scanning, which have been classified into motorized microscopes and scanners. This article describes technical aspects of 31 different digital microscopy systems. The most relevant characteristics of the scanning devices are described, including the cameras used, the speed of digitization, and the image quality. Other aspects, such as the file format, the compression techniques, and the solutions for visualization of digital slides, (including diagnosis-aided tools) are also considered. Most of the systems evaluated allow a high-resolution digitization of the whole slide within about 1 hour using a x40 objective. The image quality of the current virtual microscopy systems is suitable for clinical, educational, and research purposes. The efficient use of digital microscopy by means of image analysis systems can offer important benefits to pathology departments. PMID: 17041192.