Here is a link for the 2010 Preseason schedules. Times and specific dates not yet set.
2010 preseason schedule to feature entire 2009 playoff field
RedskinsDotCom
RT @RedskinsBlog #Redskins 2010 preseason schedule: Week 1: Buffalo, Week 2: Baltimore, Week 3: @NY Jets, Week 4: @Arizona. #NFL
Not an especially interesting preseason to me...