The issue has been bandied about the web after the claim was first posted on Slashdot last week.
Writing in his bog, Chris Wilson, Vole's group program manager for IE, said the claim was pants. He said that the story was based on an article Paul Thurrott wrote in August 2005 and was long out of date.
Wilson told ZD Net that he got a little frustrated with the Slashdot post. When Paul Thurrott wrote that original story, Vole had just released IE7 Beta 1. Vole has been making CSS and HTML improvements, but was not adding any proprietary features. He said Microsoft was doing a lot of work trying to improve its standards support.
Wilson admitted that it was difficult to have an analysis of exactly where Microsoft stands as to supporting or complying with CSS because there isn't an official test suite.
Wilson said that Microsoft was more interested in removing the "ton of bugs" from IE6 that were causing web developers a lot of pain. This was a little more important than passing the Acid2 test that The Web Standards Project did, Wilson added.
He said that as far as the CSS 2.1 spec IE's latest beta 3 is between 50-90 percent compliant.