You could argue that Hibernate is the standard in real terms, if you accept that a standard is that which most people use. JDO may be Sun's prescribed way of doing things but Hibernate is much more mature, better supported and much more widely used. Since its inclusion into the
JBoss group too its become more credible. Go with what works best - remember that Entity Beans, who's failings are very probably the reason why JDO and Hibernate are necessary, is a Sun standard too.