Sure. You still get back links if you reply to a blog post. You still get human visitors who are going to see and click.
If you're interested in getting back links for pure search engine purposes, then the answer is the yes and no. Yes if you comment on blogs that don't use nofollow. No, if you comment on blogs that use nofollow.
Many bloggers are adopting the "Nofollow Free" notices. That is, if they don't use Nofollow, they may place a logo or small note saying so. There's a list of WordPress plugins that remove the NoFollow tags from comment links: http://andybeard.eu/2007/02/ultimate...rackbacks.html
if the comment is useful, and the link is to a relevant, useful site - there's always a chance of getting visitors, and a chance that the owner of the blog may notice your site, which could lead to "do follow" links in the future...
Nexcess - Magento and Wordpress Hosting Specialists!
Commets must be meaningful and in favour of blog post. the worst anyone could to is to spam good blogs as a way to get backlinks. That's why Google changes its algorithm on regular basis. Because millions think most how to get ranked isnted of how to get recognized as a good resources.
I've closed comments on my blog only because many people think that since it is high ranked that means they need to post non-sense comments like "Hi, Thanks you for the great article. Visit ..."