In a case with implications for the freedom to blog, a San Jose judge tentatively ruled Thursday that Apple Computer can force three online publishers to surrender the names of confidential sources who disclosed information about the company’s upcoming products.

Santa Clara County Superior Court Judge James Kleinberg refused to extend to the Web sites a protection that shields journalists from revealing the names of unidentified sources or turning over unpublished material.

Kleinberg offered no explanation for the preliminary ruling. He will hear arguments today from Apple’s attorneys and the Electronic Frontier Foundation, a San Francisco digital rights group representing two of the three Web sites Apple subpoenaed—Apple Insider and PowerPage.

The case raises issues about whether those who write for online publications are entitled to the same constitutional protections as their counterparts in more traditional print and broadcast news organizations.

Apple sought subpoenas against three online news sites that focus on its products: ThinkSecret, Apple Insider and O’Grady’s PowerPage, seeking information about the person or persons who leaked information about an unreleased Apple product, codenamed “Asteroid.”

Apple maintains the information is an Apple Trade Secret, and neither the First Amendment nor California’s Shield law apply to web sites.