Why don't the YC people open up the site code and put it on github so we can contribute into making a better site?
http://arclanguage.org/install
The HN source code is in the Arc language. See my site http://files.arcfn.com/doc/index.html for Arc documentation, specifically http://files.arcfn.com/doc/srv.html for the web server internals (including why links expire). Also see the App Server page which explains account management.
If you want to hack on this, there's a small but enthusiastic Arc community at http://arclanguage.org/forum
Now, if any fix is written, where is it to be submitted?