It would be nice to have a plugin written for Jira that would complement the Hudson plugin: this would, for
once, give the possibility to avoid clutter in comments on the Jira issue, and would open doors for tighter
integration.

See an example of clutter here: http://jira.magnolia-cms.com/browse/MAGNOLIA-2414 - my few comments
are barely visible. Having a separate "Hudson" or "Builds" tab would already be a huge improvement.

See an example of what can be done:
http://developer.atlassian.com/jira/browse/JCHART-221?
page=com.atlassian.jira.plugin.ext.bamboo%3Abamboo-build-results-tabpanel

If I get some time... at some point... I'd be willing to do and contribute this The Jira plugin API is documented
enough to get started quickly.

Also, this might be a great source of inspiration:
http://confluence.atlassian.com/display/JIRAEXT/JIRA+Bamboo+Plugin
http://svn.atlassian.com/svn/public/contrib/bamboo/jira-bamboo-plugin-v2/trunk/