the press release itself has very little value according to matt cutts. however, if some authority sites pick up your press release its very good for seo.
Its all about the quality of the press release. Many news websites use each others and if you submit something good often other websites can pick up and use it especially if it gets in Google News. You can submit your press release free to: http://www.release-news.com after review your release will appear in Google News instantly
Press releases are good to attract the attention of editors of different newsgroups which may help in spreading the contents by writing about it. Its really hard to achieve this and if you really want some good results just go for paid sites instead of free ones.
press releases can help in branding and aslo in search engine optimization, you can leave a link in the end of press release
What are the odds that a press release will be picked up by major sites? Do major newspaper chains actually get content from the press release sites?
My last press release was picked up by a variety of sources that I didn't think would ever be grabbing that info. Definitely gave the site a short term boost and a few links for long term boost too.
I Thinks the Press Release is the One of the News for Website, Company, Product. Press Release is the Useful for getting Traffic and Back links.