Journalists and reporters who write for major newspapers, magazines, and broadcast news (tv & radio) have to answer to their editors and their organization’s legal team. While they have obviously manufactured evidence (CBS/Rather), there is some organizational structure in place to lessen the likelihood of manufactured confidential sources.
The same can’t be said of independent Internet bloggers. That doesn’t mean they shouldn’t be shielded; they should. Without editors and legal teams to review their claims, it is inherently easier for bloggers to manufacture confidential information.
But that just goes to credibility. The blogger should have to earn the trust of readers before they should accept anonymous or confidential sources at face value.