"There fine to drink... I've spent the last several years collecting and aging beer. There is nothing in beer that can harm you even after it has expired. A warning for you however... If it is cheap beer it may not taste good. Cheaply made pale lagers are designed to be consumed fresh and don't stand up well to the cellaring process"
http://answers.yahoo.com/question/index?qid=20080416114815AAnQT99