Full disclosure - I work for PR Newswire.

First I'd suggest thinking 'content' rather than 'press release' and apply all the best practice to it that you would to content on your own website, i.e. who is the target audience, what problem are you solving for them, do they value text or multimedia, is the content unique and compelling, and what do you want them to do with it?

Second, use online distribution as part of a strategy to create a broad link profile; too much of any one thing can be bad for you.

Lastly, look for distribution services that publish your content widely and to relevant and authoritative media as this will give you the best spread and likelihood of reaching your target audience.  Online PR works and we've had success using it to promote our own content and growing the audience for our blog.

PRNewswire.com was listed in the original Sistrix post and was indeed hit, though not nearly as badly as their data suggested.  Overall the site is down ~20%.  We're obviously not a content farm, but we do have a ton of content on a vast range of topics, and therefore a very dynamic set of keywords.  We've alerted Google and I have some theories as to why we were targeted, but we're still picking through the data so forgive me for not sharing them until I'm more certain.

Cutt's and Singhal's comments re external testers were fascinating.  If they've really codified qualitative factors that accurately quantify a user's experience on a site/page then that is going to get very interesting.  SEOs will have to grow natty little goatees and start calling themselves Optimization Experience Designers...

Hi Shailendra, let me know how you get on, it's always great talking to people who use our stuff.  My email address is in my profile.

Cheers

Rod

Hi Spencer,

Full Disclosure: I work for PR Newswire

What's dead about press releases is the old send and forget, broadcast model.  As part of a set of communications tools that includes social media, use of compelling images and video, tells a story well, is focused on what the audience is looking for and provides relevant and tangible calls to action, then press releases can be an extremely effective.  Press releases are content and their use needs to be optimized, tracked, assessed and revised as much any other.

If you're looking for tools, look for those that give the best measurement.  If you can't measure what effect you're having, how do you know the tool is working?

Cheers

Rod