Customers who use the trackbacks functionality in JIRA should be aware that trackbacks will no longer be a supported feature in JIRA 5.0.

Trackbacks are being replaced with a Remote Issue Links
Remote Issue Links allow users to add a link to any URL from a JIRA issue. For external applications, there is a simple REST API for Remote Issue Links to add a link to a JIRA issue, and JIRA plugins can use the Remote Issue Links Java API.  

For customers who used trackbacks to link from a Confluence Page to a JIRA Issue, this will be supported by Confluence 4.1 and JIRA 5.0 using Remote Issue Links:  adding a JIRA issue key to a Confluence page will automatically create a Remote Issue Link from the JIRA Issue back to the Confluence page.  As a part of the upgrade to JIRA 5.0, any trackback URLs will be migrated to Remote Issue Links.

In addition, Remote Issue Links will support links from one JIRA instance to another JIRA instance, so an issue on a JIRA instance can be linked as a duplicate of an issue on another JIRA instance, making the use of multiple JIRA instances much more valuable. End Users can also now more easily add links from a JIRA issue to any external URL.

Remote Issue Links also provides a greater level of security. Both in the UI as well as via the API, links can only be created by users who have the Link Issue permission, which prevents the anonymous spam that often occurs with trackbacks.

Bryan Rollins
JIRA Product Management