Yes, I used all of those type sites.  PR Newswire, PR Today, Free-pressrelease.com

 

there are so many ...

 

I find it best to submit to all of them.  In addition to strategically targeting different publications that are specific to your product, as I have recently discovered. 

You may also want to check out www.prweb.com and my list of free posting sites at http://rembrandtblog.com/2008/04/18/40-no-charge-sites-for-your-press-release/.

Thanks,

Melanie

You've discovered one of the keys to getting publicity.  Just like the three keys to real estate success (before the bubble) are location, location, location, the keys to publicity success are target, target, target.

Another way to broaden your target is to think of how-to press/releases you can create.  For example, if the software has a biz application, write a press release on how iPhones can be used to enhance productivity.  It's not a direct sell of  your product, but if gives you a chance to spread the word and position yourself as an expert.