Those who’ve speculated that the Internet heralds the end of investigative journalism may not have been following the recent work of As the blogging arm of the Center for American Progress, ThinkProgress is neither a traditional news outlet nor an independent blog, but rather an engine of progressive reportage that has already shaped the national debate on several important issues.

That in its six years ThinkProgress has ruffled some feathers became apparent last week when the blog released emails it had obtained between the Chamber of Commerce and lobbying firm Hunton and Williams. Hunton and Williams had solicited the services of a set of private security firms collectively known as Team Themis to attack the Chamber’s opponents. The emails reveal that the Chamber has engaged in a calculated smear campaign against numerous progressive organizations, including ThinkProgress itself.

In an attempt at character assassination, the Chamber’s lobbyists have gathered private information on the Chamber’s critics and political opponents by such means as scouring the Facebook accounts of their children and spouses. Thinkprogress also published documents that indicate Team Themis proposed to create and circulate false financial documents attributed to progressive lobby groups and to invent fake “insider personas,” all in an effort to undermine and discredit these groups.

The Chamber of Commerce, the leading lobby for corporate interests on Capitol Hill, pledged to spend $75 million to influence the 2010 campaign cycle — a sum that dwarfed the spending of any other issue-based advocacy group and many candidate warchests.

An investigation ThinkProgress conducted before the election revealed that a vast quantity of the Chamber’s funding comes from foreign sources, in potential violation of campaign finance law. That investigation likely made ThinkProgress a target of the Chamber’s subsequent dirty tricks.

The damning emails were first made public by the online hacking collective Anonymous. (A detailed account of how they hacked the HBGary servers can be found here.) Anonymous targeted HBGary Federal, a cybersecurity firm involved in what ThinkProgress has dubbed the “pro-Chamber conspiracy,” after the CEO of the firm, Aaron Barr, told the Financial Timesthat he had penetrated the Anonymous group. Anonymous promptly hacked the email and Twitter accounts of HBGary and posted hundreds of company emails on its WikiLeaks-style site, AnonLeaks. Among the documents obtained was a PowerPoint presentation entitled The WikiLeaks Threat that presented strategies for sabotaging WikiLeaks on behalf of Bank of America, including “disinformation,” “cyber attacks,” and “sustained pressure” on the media.

ThinkProgress journalists Lee Fang and Scott Keyes quickly combed through and analyzed the AnonLeaks document dump and unraveled the narrative behind it. “This story wasn’t discovered and driven by the New York Times and the Washington Post,” Keyes told me. “It was done so by blogs and interested citizens.”

Unlike many news outlets, ThinkProgress has an explicitly liberal political agenda. This, Keyes said, has “liberated” ThinkProgress bloggers “to simply investigate stories for the truth of the matter” rather than having to “always give both sides an equal microphone without any regard for what the truth is.” In an age when far right media sources like Fox News make broad claims to objectivity, ThinkProgress, at least, offers full disclosure — and thorough source documentation. “We’re not a partisan organization in any sense,” Keyes said. “What we are is an ideological organization, dedicated to improving people’s lives through progressive ideas and actions.” In defending the blog’s nonpartisan bona fides, Keyes pointed me to multiple posts that have slammed Blue Dog Democrats who have sought to block theeconomic stimulus or financial regulatory reform, or who voted for the repeal of health care reform.

ThinkProgress has pulled off some notable scoops. In 2009, in the midst of the battle over Obama’s health care plan, the site was the first to report on Dick Armey’s dual role as a lobbyist for pharmaceutical companies such as Bristol-Myers Squibb and chairman of FreedomWorks, the Koch-funded outfit that organized “grassroots” attacks on health care reform. In the midst of the ensuing media coverage, Armey left his job at lobbying firm DLA Piper. And the bloggers kept up a steady drumbeat exposing the central role such Astroturf groups as Americans for Prosperity played in the protests themselves.

ThinkProgress has investigated the political spending of oil companies, revealing that the Chamber and other business lobbies receive massive amounts of funding from big oil firms, here and abroad. Those posts, and a linked report from the Center for American Progress, attracted the attention of then-Speaker of the House Nancy Pelosi, who issued a statement headlined, “Connecting the Dots: Secret Money, Corporate Special Interests, Big Oil Profits” that cited Thinkprogress reporting. The blog uncovered that an evangelical group of climate change deniers, the Cornwell Alliance, was funded by oil companies. And in recent days, ThinkProgress has been among the journalists who’ve traced the far-right corporate moneybehind Wisconsin Governor Scott Walker’s anti-union agenda.

ThinkProgress has also served as a media watchdog, documenting the inconsistencies of right-wing pundits and factual errors broadcast on Fox News, and being the first to note, for example, that Sarah Palin was reading notes off of her hand during a TV interview. (She still got the facts wrong about the cost of extending Bush’s tax cuts). Just before the miderm elections, ThinkProgress reported on the funding and players behind the Republican National Trust PAC, which ran 25-minute long Obama attack ads on FOX stations that invoked Mao and Hamas to paint the president as a “socialist.”

“ChamberLeaks” may be a sign of things to come in investigative journalism after WikiLeaks. The story was created and reported outside the mainstream by online journalists whose stake in the story was clear — but who also got the goods.