From windowsvistablog.com
"Microsoft has said that Windows Vista SP1 is released to manufacturing and it should become available on Windows Update and the download center mid March."
Service Pack 1 promises great progress in performance, reliability and compatibility. Copying files within a PC or across a network will be up to 50% faster.
In mid-March, Microsoft will release Windows Vista SP1 to Windows Update (in English, French, Spanish, German and Japanese) and to the download center on microsoft.com. Windows Update visitors can choose to install Service Pack 1. If Windows Update determines that the system has one of the drivers known to be problematic, then Windows Update will not offer SP1.
June 2019 update Now that Windows Vista is long gone, it's time for a history lesson: What Happened with Windows Vista?