To the best of my knowledge Microsoft hasn't yet committed publicly to support SVG, the Scalable Vector Graphics technology from W3C. See Scalable Vector Graphics (SVG) for further general information.
Interestingly, the GIMP has recently added SVG support. See GIMP goes SVG on Slashdot.
Posted by Andrew Watt at October 8, 2003 12:15 PM
Microsoft Visio 2003 supports SVG for import and export.
http://www.microsoft.com/office/preview/visio/overview.asp