As part of the result from Microsoft's anti-trust litigation with the U.S. government, the Redmond giant is currently subject to oversight to ensure that it doesn't abuse its market position. While there are numerous decrees that govern this arrangement between Microsoft and the various government entities involved in the oversight, most of those agreements were due to run out in late 2007.
It seems that the government bodies are still not 100% confident in Microsoft's ability to operate without running into anti-trust issues and thus are extending their arrangement for a few more years.
"A federal judge ruled Tuesday that a consent decree enforcing the settlement would remain in effect until November 2009. A group of 10 states led by California and New York had requested the oversight be extended until November 2012."