I've noticed one press release come out of PR Web exclusively advertising a "premium" domain for sale. I don't think the domain was actually premium, but the vast majority of the general public might not know the difference.
PR Web is a B2C wire service. Their feeds are free and lots of sites run their feeds for content. I wouldn't seriously have any expectations of the story getting picked up by real media outlet, but you can expect some traffic and attention (assuming your domains are of interest).
Is your domain one that you are hoping to have a real news service pick up the story? If so, you might want to consider PR Newswire or Business News Wire. They're much more expensive, IIRC, but their primary audience is news rooms and media industry ppl like journalists and desk editors who are looking for new story ideas and filler pieces.
Also, you're going to want to have a professional write your press release -- there's a little bit of an art to it.
