The statement, released by the EC this morning, explains that "in light of changes in Microsoft's behaviour, the increased opportunity for third parties to exercise their rights directly before national courts and experience gained since the adoption of the 2004 Decision, the Commission no longer requires a full time monitoring trustee to assess Microsoft's compliance." They added that "in future, the Commission intends to rely on the ad hoc assistance of technical consultants."
The EC further explains that the interoperability information Microsoft had to publish has all been released, and as such, direct monitoring is no longer required. The really juicy part of the statement is the wording: "the original set of interoperability information has already been documented by Microsoft". This is the first official admission from the EC that Microsoft has complied with its ruling - and apparently, it did so in the past.
In any case, this is of course separate from the whole Internet Explorer issue the EC is currently investigating, which Microsoft might thwart by allowing users to remove the browser from Windows in Windows 7.