The government of Brazil announced a change in the observance of daylight saving time in the country. According to the details in the Ministry's Decree number 6558 of September 8, 2008, DST there will start the third Sunday of October and then end generally on the third Sunday of February of the following year. As confirmed on Brazil's Ministry of Energy web site, the Electric Power Sector Monitoring Committee (the Comitê de Monitoramento do Setor Elétrico, or CMSE) set the new dates for DST, which will begin on October 19, 2008, and end on February 15, 2009. (See this link for more details (in Portuguese) or this link for the translation into English.)
Microsoft has created upon request, out of band release packages for Windows Vista, Windows Server 2008, Windows Server 2003, and Windows XP for the Brazil DST update, Knowledge Base Article 957201, "A hotfix is available to update the "(GMT-3:00) Brasilia" time zone and the "(GMT-4:00) Manaus" time zone for 2008 through 2009 in Windows XP, Windows Server 2003, Windows Vista and Windows Server 2008." Click here to view and request hotfix downloads.
Please note that these packages are call-in/request only packages and will not be released to the Microsoft Download Center or via Microsoft Update Services. These changes will be included in the next DST Windows cumulative package released for all currently supported operating systems (Windows XP, Windows Server 2003, Windows Server 2008 and Windows Vista), due in December.
For more details...
... in Portuguese, please see http://www.microsoft.com/brasil/windows/products/windowsvista/verao.mspx and http://blogs.technet.com/latam/archive/tags/DST/default.aspx,
... and in English: http://blogs.technet.com/latam/archive/2008/09/30/brazil-dst-2008-2009-changes.aspx and here as an XPS file.