Right now, the Microsoft IE team is struggling to get HTML 5 and SVG (2D graphics) into Internet Explorer 9. Other web browser makers have been shipping with those standards built in for years.
Apple Safari, Google Chrome, and Mozilla Firefox all run fine on Windows. Takes one mouse click to launch a different browser. Takes a year or two to see what Microsoft might do.
IE progress has consistently been glacially slow this whole decade.
No, IE does not have WebGL support now and betas from other browser makers already run it. IE9 will not catch up with contemporary web standards like WebGL, just ones that have been out for several years or more.
IE9 is not a cross platform web browser either. It will only run on certain specific versions of Microsoft Windows. Just run one of the standard web browsers and you can see what WebGL can do. Their current betas are running some impressive WebGL demos now.