There is a print exhibit at Baltimore Museum of Art that runs through March 25, Print by Print: Series from Dürer to Lichtenstein, over 350 prints from the 15th century to today in 30 complete series from the museum’s collection. The web site (uses Flash animations) has good info on contemporary printmaking and on printmaking techniques. It’s definitely worth a look.
This video is one of the best introductions to silkscreen printmaking I’ve found. It’s just under 5 minutes and gives a clear demonstration of making screen stencils and printing.