Currently in JIRA, an issue is deemed resolved (in reports, portlets etc) if it has a resolution set. This includes both Resolved and Closed issues, and generally works fine. However in JIRA 3, people can:

• Have more than one issue deemed 'closed', but which may not yet have a resolution
• Edit the 'resolve' transition (or equivalent) to not set the resolution

In these cases, the built-in assumption that resolution == closed breaks. It would be better to just have a 'closed' flag on the issue. This would also enable a number of new queries and statistics to be generated (ask Mike for details).