Illinois v. The Alton Telegraph [1]

An Illinois grand jury subpoenaed The Alton Telegraph newspaper in September 2008, seeking the  names, addresses and IP addresses of readers who posted comments to TheTelegraph [2] website under five pseudonyms. The subpoena required that the newspaper's keeper of records appear before the grand jury with the requested records on October 2, 2008. 

According to one press account [3], the state's attorney seeks this information in connection with a murder investigation that does not involve The Alton Telegraph.  The state believes that one of the anonymous commenters has information about past criminal activity on the part of the subject of the investigation.

The newspaper moved to quash the subpoena, arguing that the Illinois reporter's shield law [4] protects the identities of the anonymous commenters as "sources."  It also moved to postpone the return date of the subpoena, apparently successfully.  As of October 17, 2008, the court had not ruled on the Alton Telegraph's challenge.

Update:

5/15/09 - According to Saint Louis Post-Dispatch [5], the court ruled [6] that the Alton Telegraph must turn over the identities of two of the posters.  As to the other three posters, the court ruled that the paper need not disclose their identities because what they had written was irrelevant to the investigation.