What is article marketing?
Article marketing was born in 2000 at google.com when some guy submitted an article and it got traffic to his website.
Since then, article marketing is perhaps one of the most misunderstood bastard childs of the internet. Blackhatters used to submit garbage articles to massive directories building thousnads of crappy backlinks to their site, dominating the search engines.
Nowadays google got tired of it and does their best to lower the ranking of tricks like that, so its best to write a medium amount of high quality articles and use them for traffic and SEO, not low quality crap either.
If you write good article and submit them to only the good sites, it can be worth it. Sooperarticles, ezine, streetarticles, hubpages.