jBPM 3 core targets jdk1.4, so annotations etc will not be supported. There is a discussion whether the (current) webapp could require jdk 1.5 so we can move to using seam in the webapp. There is lots of hasitation towards that (from customers) since the webapp should achieve a certain level of stability and many companies are not ready at all to move to jdk 1.5 (see http://jboss.org/index.html?module=bb&op=viewtopic&t=96465) The reason for this is that it has been under constant redesign for the last 2 years (besides adding new functionality)
The discussion on moving to java 5 for jBPM 4 has not been (publicly) started. Don't know if this has been internally discussed yet.