It’s a well known secret that being listed at DMOZ.org is one of the most important things when getting high ranks in Google. If a site is listed at DMOZ.org, it has been checked by a DMOZ editor and can therefore be believed to have high quality. The DMOZ directory was also mirrored to http://directory.google.com (but that has been discontinued), and if a site was listed in the DMOZ directory the classification was displayed in the Google search result (apparently also discontinued).
But according to the Goggle Webmaster video at the bottom of this post, there are no extra benefits from being in the DMOZ directory, not more than a link from any other site. But DMOZ tends to have a high pagerank and the directory is also mirrored to many other sites which will build pagerank.
Back to the question.
How long does it take to get listed at DMOZ.org?
Well, the quick answer is that it depends. It depends on which category and how active the editors are in that category. If you want to add your site to the “right” category it can take about a month. If you want to add your site to the “wrong” category, I’ve read in the DMOZ forum about people waiting for 2-3 years!
I’ve experienced this myself.
Some years (more than five I guess) ago I added a several sites to the DMOZ directory and I think I had to wait a few months for each to be added. Then I created a new site and submitted it to the DMOZ directory. I waited for months and months. Then I created a subdomain to the site with content that would fit better in a different category than the rest of the site. After submitting the subdomain to another category in DMOZ it was added in about a month. The first submission is still not added after waiting more than a year. So you have to be “lucky” and have a site goes into the “right” category.
Although Google does not give any extra credit for being in the DMOZ directory, it can’t be a bad since according to this list the directory is mirrored to almost 100 different sites.