The Fourth International Workshop on Automation of Software Test (AST 2008) ICSE 2009 expanded previous programs to two days, supported a special theme of Testing Web Services, added a Case Studies from Business and Industry session, and included a charette-style work session. At the workshop, 15 regular papers and 7 short case-study papers were presented in 7 sessions at the workshop. This report summarizes the organization of the workshop as well as the sessions and papers presented, the results of the charette session, attendee feedback, and lessons learned. (This is an updated and expanded version of the workshop summary that was included in the ICSE 2009 proceedings.