The newest way to report spam isn't filling out a form on Google, its building a compelling story and pitching it to the media. I imagine that right now David Segal has hundreds of emails in his inbox from frustrated SEO companies and PR professionals pitching him the newest JCPenney. Segal wrote the article on JCPenney's use of paid links and link farms to improve their product rankings and as a result the company has been penalized and their competitors are reaping the benefits as they improve their search positions.
Using the NYT or similar publication as a channel to report your competitors will result in swift action. Google doesn't like to be embarrassed and when they are publicly confronted with evidence of competitor misconduct they will have to react or risk their reputation.
Google does provide a way to report spam and they have algorithmic and manual ways to respond to it but there is never a clear resolution. Reporting paid links doesn't result in a response of "we reviewed your report and took action" or "we reviewed your report and took no action." So in some ways using the media as a spam reporting tool is much more effective, the problem is getting in front of the right people and making sure Google takes notice of what they've written. That's why having a pr firm or well connected staff member to pitch your story is going to be important going forward.
To be reported, you don't even have to engage in black hat SEO techniques. One example that comes to mind occurred last year when a lead generation company setup a network of fake VA hospital sites in order to generate leads for asbestos lawyers. They essentially created medical sites that could fool visitors into thinking they were on an official hospital site when in fact it was a lead generation service. Roger Parloff, the reporter who covered the story, had previously written about unsavory practices in the asbestos litigation industry and another firm knew this and sent him information about the sites saying they were "cheating." Their move paid off because by the time the article was published, the web sites were taken down and replaced with under construction labels that lasted until the domains eventually expired.
Getting someone like a David Segal or Roger Parloff to publish a story about unsavory competitor practices requires a compelling story. If a local pest control company is using paid links, no one will ever publish a hard hitting expose that delves into the depths of their terms of service violations but if you have a Fortune 1000 company or someone doing something very deceptive then you have to put together a compelling story and pitch it to anyone who might listen.
Just make sure you have a catchy subject line in your email because your next great story is going to be in a long line of other next great stories.