as you probably noticed, jboss.org JIRA instance running at http://issues.jboss.org has been upgraded this week to JIRA 5 and GreenHopper 5.10.
There is lot of interesting improvements in JIRA 5 as you can see in Release Notes. Probably most noticeable are:
GreenHopper has been updated from 5.8 to 5.10, so you need to check two release notes:
Main enhancements and changes: