Integration with JIRA provides three advantages:

• You can log in on either http://wiki.nci.nih.gov or http://tracker.nci.nih.gov and you will be logged in on both sites.
• If you have editing permissions on the wiki, you can use a shortcut to display any one JIRA issue. Refer to How do I use the JIRA shortcut?
• If you have editing permissions you can also use the jiraissues macro. Refer to How do I use the jiraissues macro?

Confluence 3.5 provides improved JIRA integration, demonstrated in a video provided by Atlassian.