Not tried this but sounds interesting - Press Release Grader. If you try it share your thoughts by commenting here.
On a related subject, there's been talk for a while about the 'social media press release template' of which I'm a little skeptical to be honest - I love the idea of press releases in a social media context but let's not template ourselves to death. To me digital media is a constantly evolving thing that defies rules. I agree with Andrew Smith on the subject (the connection is down in paragraph ten - but it's worth reading your way down to it). Let's experiment.

I have just tried the grader, expecting it to be very very wrong (or telling me one of our releases was rubbish), and it was actually quite a funky tool.
The release I put in this week got mainstream national coverage in Torygraph, Metro, Mail, Daily Express and various glossy mags and according to the grading tool it scored 95 out of 100! Wooooo
Posted by: Andy Barr | June 13, 2008 at 14:37
What a great idea for a PR tool. The home business owners who visit enterprisenation.com will love it. Thanks, Daryl.
Posted by: Emma Jones | September 07, 2008 at 20:18