It is linked - the whole title is a link to the OP on all my linked posts. I often refer to the post in the article body too, but forgot in this case. I've fixed that now.
No worries, you're not the first one to get confused! Funny thing is, I copied John Gruber's model (see http://daringfireball.net ), and it seems to work very well for him. Not sure why people get confused on my site and not on his (but maybe they get confused there too!)
I want the title to be linked to the destination article so they get any link-juice I may have to give associated with the article. The little star thing next to it is the permalink.
It wasn't linked from the OP, so I had to trawl for it on Twitter, where it is sure to get lost within a few days.