There are many threads on this topic around here, this is just one of them: http://forums.digitalpoint.com/showthread.php?t=141761
is your press release already written ( and you are looking for submissions only ) or you need both the tasks to be done ..!!
That would depend on whether you want it sent out for media placements or not. If so, you can submit pretty easily yourself just to one of the big distribution sites (www.PRnewswire.com, www.prweb.com, etc.) and upgrade it for added exposure. You should certainly email it to your regional AP office if it's newsworthy enough (www.ap.org). If you're just looking for someone to post it on as many free sites as possible, you could check with a few of the content writers around. Some probably offer some kind of distribution service for articles and could do the same for releases (try DeniseJ and InternetAuthor - not positive they do submissions, but they might).
www.prweb.com proved to be the best quality for the lowest price when we did our search. They will write the article and optimize it for you and submit, or you can write it, and have them optimize it,....or you can write it yourself and submit it yourself. The options above are from the most expensive to the least. Hope it helps e