I would like to be able to specify Jira setup(s) to Confluence settings and then be able to search from those Jira instances as well. This could be represented as a separate search type 'Issues' that the user could opt out in the search. If there we multiple Jira setups connected to Confluence then there should be an option like the 'Select space' to search in. Users could selected either all or some Jiras to search from. Additionally there could then be more configuration options for the Jira searches (Jira search options: projects, issue types etc.).

This way all information would be accessible and searchable from Confluence. It would be a lot easier to find the information that users are searching for since then there would really be just one place to search from.

See: http://confluence.atlassian.com/display/DISC/Integrate+Confluence+Search+to+Jira+Search

This could be done over the remote api as well JIRA:JIRA XML-RPC API Spec (http://confluence.atlassian.com/pages/viewpage.action?pageId=1035) and
http://confluence.atlassian.com/pages/viewpage.action?pageId=1035&focusedCommentId=43490#comment-43490