A new plugin I created for alexking.org 2.0 is a simple banner to indicate the age of the post that is shown in the comments form1. This is one of the changes I made to add context that I forgot to mention on my navigation post. To see it in action, browse the archives here.
The download is available on my WordPress Plugins page.
If you have any trouble with this, please open a thread in the WP Support Forums and send me the link.