Karon Thackston wrote a compelling article on using press releases for more than just buzz, but also considering their development as a traffic generator for your site.

Karon recommends considering the following elements when writing a multi-purpose press release.
1. Have a narrow focus.
2. Include copy that deals with one specific topic.
3. Incorporate the use of keyphrases.
4. Use keyword-rich headlines.
5. Choose keywords that can be easily included in your release.
6. Incorporate keywords into your headline where possible.
7. Incorporate press releases into your blog
8. Create a seperate HTML page for each press release

Related Resources:
PR and the Web: The Case for a Robust Online Newsroom