yes in a way if you use the free ones they are kind of like article sites. Now most go a different way on posting press releases.
Now there are a few different type of press release that you can do. You can do the post to all the free news sites that IMO are junk because they get spammed just like all the article sites. Now they are counting less and less.
If you have a real press release then there are a few companies that you can go to that will submit the press release to different news stations and so on. You can do this yourself if you have time. Most of these never get covered in the news but they do tend to put the press release up on the web.