The Department of Justice has been hounding Microsoft for years over anti-trust issues of one sort or another, not to mention the major case in the late '90s that had people wondering if MS was going to be broken into several smaller operating units. Apparently that's all changed:
"Nearly a decade after the government began its landmark effort to break up Microsoft, the Bush administration has sharply changed course by repeatedly defending the company both in the United States and abroad against accusations of anticompetitive conduct, including the recent rejection of a complaint by Google.
The retrenchment reflects a substantially different view of antitrust policy, as well as a recognition of major changes in the marketplace. The battlefront among technology companies has shifted from computer desktop software, a category that Microsoft dominates, to Internet search and Web-based software programs that allow users to bypass products made by Microsoft, the world’s largest software maker."
Microsoft seems to have a new ally: Thomas O. Barnett, who is the Assistant Attorney General and former partner in the law firm that represented MS in anti-trust issues until his departure in '04. Obviously any involvement on his behalf might be seen as conflict on interest, but he's already made it clear that he had no involvement in the MS case.
The most notable thing the Barnett has done in regards to Microsoft of late is to send out a memo to all State Attorney Generals that allegedly dismisses claims from Google that MS and their Vista search slow down the search functionality in Google Desktop. It is unclear at this time how many state governments will hear Google's complaint and act upon it.