It wouldn't take too long to knock up an application like this using CoreData from all the examples I have seen. Of course if you go that route it will only run on a Mac (10.4 and higher). Concierge seems to be intergrated into the apple website too, I don't know how this functionality it to be achieved, it that something you want too?
Have a look at this<a href="http://www.cocoadevcentral.com/articles/000085.php">CoreData Blogging Example Application</a> for some more ideas.
