The earlier decision, made by Judge James Kleinberg of the Santa Clara County Superior Court of California, had been appealed by the Electronic Frontier Foundation, which, along with co-counsels Thomas Moore III and Richard Wiebe, represented the sites.
A similar case against the site Think Secret is still under deliberation.
The May 26 decision stated that PowerPage.org and AppleInsider are protected under First Amendment rights as well as by Californias own reporters shield law.
There currently is no national reporters shield law in the United States.
"We can think of no workable test or principle that would distinguish legitimate from illegitimate news," the judges wrote in their decision.
"Any attempt by courts to draw such a distinction would imperil a fundamental purpose of the First Amendment, which is to identify the best, most important, and most valuable ideas not by any sociological or economic formula, rule of law, or process of government, but through the rough and tumble competition of the mimetic marketplace."
In March 2005, Judge James Kleinberg of the Santa Clara County Superior Court stated that the rumor site owners did not have the right to protect their sources.
Apple had brought suit against the Web sites in December 2004, claiming that the sites had published confidential information relating to an unannounced product, code-named Asteroid.
The company filed its complaint under the California Trade Secrets Act, which in March 2005 was enforced by Kleinberg, who wrote that "trade secret laws apply to everyone regardless of their status, title or chosen profession."
In addition, the appellate panel sided with the EFF in overturning Kleinbergs allowance of Apples subpoenas to Nfox, the company maintaining e-mail services for PowerPage.org.
Apple had sought Nfoxs records, hoping to uncover the identity of PowerPage.orgs source or sources.
However, the appellate panel stated that this subpoena violated the Federal Stored Communications Act, in that it did not subpoena directly account holders.
The EFF has posted the text of the full decision, here in PDF form, on its Web site.
Said Jason OGrady, owner of PowerPage.org: "Its obviously a huge win for me and the PowerPage, but more important is the fact that the appellate court recognized the reporters shield and the constitutional privilege. So its an important decision for all members of the media; had our petition been denied, it would have set a dangerous precedent."
"This is a great decision. Its a victory for journalists whether theyre online or offline, because it protects and preserves the confidentiality of sources on which all journalists depend," said Kurt Opsahl, attorney for the EFF.
However, this is not the end of the legal road, said Opsahl.
"This is just about discovery for the journalists. Apple is free to pursue its case by other means in the Superior Court. Also, Apple might consider petitioning for appeal to the California Supreme Court."
He added that Apple has 40 days to appeal the appellate panels decision.
Apple representatives did not return calls in time for publication.