Well, that depends why you want to take the exam in the first place. If you want to do it to make yourself study/learn
ejb's (kind of obligating yourself to do it) it is maby better to wait for ejb3.
On the other hand, if you just want the 'paper' (my case) then I wouldn't wait for EJB3. You can always read the spec and study EJB3 when it comes out and if you know (and can use) EJB2.x it will not take much effort to understand the differences.
I think it comes down to this: do you need to get certified any time soon ?
[ July 20, 2005: Message edited by: Koen Serneels ]