Disqus is an interesting service that fills a very web-2.0-style role. There's a zillion sites out there which support the users leaving comments. The web 2.0 model has community involvement front and center, contrasting with the old model of businesses pushing content or services or products at you. But the problem with this is having to register with each and every website on which you want to leave comments.. and further site administrators dealing with comment spam and desiring a better solution.
"Disqus, pronounced "discuss", is a service and tool for web comments and discussions. The Disqus comment system can be plugged into any website, blog, or application. Disqus makes commenting easier and more interactive, while connecting websites and commenters across a thriving discussion community." That's what they say anyway. What they do is offer a service platform where cooperating websites gives control over their comments function to the Disqus service. A "leave your comments here" box appears on the site but that box is managed by Disqus's service. User authentication is handled by Disqus and the comments live in this place that appears on multiple webistes including Disqus's own.
Each user of the Disqus service has their own profile page hosted by the Disqus service. The profile page lists a snapshot of who they are, an avatar, and a running listing of comments they've left on other sites. The profile page also links to the account owners own website allowing someone to find a comment, get to the commenters profile page, see other comments they've left, and also get to their own web site.
Disqus also has integrated support with other services. Using Seesmic a video comment can be left, not just textual. Disqus can also forward comments out to other services like Facebook, Twitter, Del.icio.us, etc.
The Disqus service is installed by adding a module to whatever blogging (content management system) platform used on each website. The next step is to register that site with Disqus. However for a Drupal user browsing the Disqus site you might think Drupal users are out in the cold. The Drupal Disqus Module is pretty easy to install and provides the required integration.
Simply download the tarball to your webserver, unpack and enable the module like normal. Once enabled a Disqus choice shows up in the administration area, and you simply enter a couple values to get going. However you must first go to the Disqus site and register your site with Disqus. During the registration process Disqus generates a short name for your site derived from the domain name. You then enter that short name in the registration field of the module settings page. You also select the content types for which Disqus comments are to appear. The final step is to go into the User Permissions section and enable view permissions for the roles you wish to utilize Disqus commenting.
Those are very simple and obvious steps to take. Once taken a new comment box appears below your content, replacing the existing comment box. However if your site has existing comments those do not poof into a cloud of greasy black smoke, they still exist.
I have a couple qualms..
First is that in the Tracker page Disqus comments do not appear in the count of available comments. A post which gains a Disqus comment is not marked in Tracker as having had a comment. I haven't figured out yet how to determine from the Drupal site which nodes have had Disqus comments attached to them.
Next, what if (when) the Disqus service dies. Their service has no apparent revenue stream (e.g. no advertising on their site) hence they're burning through seed capital. Maybe their service will die if they don't get funding. If so, what happens to the comments? What happens to the user relationships you've built up. Your community in other words is in the hands of a third party, and your livelihood related to that community is dependent on Disqus staying in business.
What if Disqus is bought by another company? The service might continue in operation but is most likely going to change names. e.g. "Google Discussions"... The disqus.com based service URL's will also change. Assuming the purchasing company does a good job and keeps the service running, switching service URL's etc is a small matter of recoding the module. But there's no guarantee of anything most especially that a purchased service will be kept alive.
Still, looks very valuable. It's enabled on this site for the time being.