Current information on GIS vendors and products are available in several publications.
Trade journals are also a source of current information.
You may want to assign an exercise in which students will assess different products on the characteristics that are discussed here. A Survey of Geographical Information Systems for Natural Resource Decision Making, Washington. Useful if fugitive survey. Includes an excellent summary of current GIS products and vendors listing cost, date first introduced, support, data structures, functionality. An update will be published in 1990 and may continue to be an annual publication.