It's EXTREMELY effective. I just wrote an article and published it to my favorite article directory. Within a few days, the article itself was listed #8 on Google for the keywords I targeted!!! (Very important keywords for my site.)
That same day, I saw the site that I linked to in my artcle (that I was trying to promote) listed as #6.
I was ecstatic and decided that I'm going to do this a lot more often.
If you learn how to do it the right way, it's incredibly effective. So many people are doing it the wrong way though.
They are submitting to 100's of sites with software and going for the quantity over quality spammy type of crap. NO NO NO! The key is just to use the right keywords and most importantly, the title. Then properly link back to your site in the resource box with the right keywords.
This whole technique is an art form. Perfect and get tons of targeted traffic back to your sites from the article directories and mostly from Google!!!