After much banging away with bugs and lots of head scratching one some of the Clearspace APIs, I have a basic Jira Issues macro!
The macro output is a Flex widget, and so the plugin must proxy requests (Flex cannot connect off-server without a crossdomain.xml permission file on the remote server.)
{timojira:url=<Jira server XML feed url>}
{timojira} -- without a Jira URL, it will display some sample data (good for troubleshooting, or quick tryout)
Cache, oh how I wanted to implement thee... but alas, another day for you!
Cheers,
Timo
Screenshot

Clearspace 1.X Plugin Files Attached Below