The website supports comment posting using trackbacks. The comment posting also supports just regular comment posting, but I don't have a form for submitting them yet. Trackbacks allow you to post replies on your blog, as a response to an entry on another site. Basically, inter-site commenting.
Trackbacks are a great standard. They're simple and easy to implement and well documented. Basically, a Trackback is implemented as a form which takes 4 fields (excerpt, url, blog_name, and title). The response is a simple XML format with "error" and (if error is non-zero), "message" elements.
When you post an entry on your own site, which is related to an entry on another site, you send a Trackback "ping" to the other site. That ping is the form submission as described above.
The other component is the Trackback Autodiscovery. This is some simple RDF code that you put in the page which contains your entry. A posting tool that supports Trackback autodiscovery can take the URL for a entry, and figure out how to submit the ping to allow linking the entries.
It does exactly one thing, simply and easily. Better, it adds significant functionality to existing tools. It took roughly 2 hours to implement for our site, and that was with being distracted by chatter on IRC.comments powered by Disqus