It shouldn’t. All the tag is doing is telling Google and MSN and any other search engine who honors the tag not to use the description from the DMOZ when they show your pages in search results. Obviously if you’re site isn’t listed in the DMOZ this tag won’t do much. Some people listed don’t think their DMOZ description matches well with what should show under their link in search results. For some the company has changed since they were accepted into the directory or they simply didn’t approve of how an editor at DMOZ described their site.

I’d seen some say that using this tag might associate your site with SEO in general since most site owners will probably never be aware this tag exists and that being associated with having a site that’s been SEOd might not be something you want a search engine to think about your site.

However the tag isn’t meant to work that way and it shouldn’t affect where your pages rank for specific keyword phrases. Still I’d only use it if you’re site is currently listed with DMOZ and you’re unhappy with the description there.