Although a first Longhorn beta release is still a number of months off, it's not too soon to begin considering whether the next version of Windows might violate antitrust concerns.

That's the view of the U.S. Department of Justice and a handful of state governments, which settled their antitrust case against Microsoft in 2001. As part of the settlement, the plaintiffs and an appointed technical committee have been charged with monitoring Microsoft's compliance with the settlement.

On Tuesday, the plaintiffs filed their fourth of the six-month joint status reports requested by the U.S. District Court for the District of Columbia. In it, the plaintiffs noted that they will hold the first of their briefings with Microsoft in mid-February on how Longhorn will comply with terms outlined in the final antitrust judgment.

"Plaintiffs have prepared a list of topics that relate to the final judgments that plaintiffs wish to track as Microsoft progresses in its development of Longhorn, enabling early detection and resolution of any potential areas of concern," according to the status report.

The plaintiffs provided this list to Microsoft, and the company has agreed to brief them regularly on these topics, the report said. The briefings are expected to continue throughout the Longhorn development and test cycle, according to the report.

Longhorn client is expected to go to external beta testers in the second or third quarter of this year, according to sources. Microsoft is expected to ship the final release by the third quarter of 2006.

Read more here about the Longhorn delay and how it's affecting developers.

The joint status report included a number of updates on other Microsoft monitoring efforts.

Since the last full status report, filed July 9, 2004, regulators have received 23 complaints involving Microsoft's compliance with the final antitrust judgments. But the plaintiffs found all 23 complaints to be non-substantive.

On the Windows XP SP2 (Service Pack 2) front, in terms of how Microsoft's most recent service pack deals with competing middleware and defaults, the plaintiffs have found some areas for concern, according to the report.

The technical committee "has identified several circumstances in which further information from Microsoft is needed to determine whether Windows satisfactorily honors user middleware choices," the report said, without offering further specifics.

Additionally, the plaintiffs have finished their review of Microsoft's Market Development Agreement, the contract that covers Microsoft's pricing and licensing terms required of Windows OEMs.

Sometime in the next several months, Microsoft is slated to release the next version of its uniform OEM Windows licensing agreement, the report said. The plaintiffs "have not discovered any issues that require further investigation" on this front, according to the report.

The Microsoft Communications Protocol Program continues to be an area of close scrutiny. Microsoft reported that two additional companies—Unisys and vBrick Systems Inc.—have signed MCPP licenses since the last interim status report, bringing the total number of MCCP licensees to 21.

But a number of companies have continued to complain that the MCCP is not providing what it should: equal access to Microsoft's communication protocol information in a way that does not discriminate against open-source vendors and other Microsoft competitors. The technical committee is stepping up its work to evaluate complaints against Microsoft in this area, according to the status report.