The IE10 will officially be released on 26.10.2012 along with Windows 8 and doesn't support WebGL. As far as I know Microsoft hasn't made any announcements about IE11, so it is unknown if IE11 will support WebGL.
But IE10 supports typed arrays, which can be seen as a sub-spec of WebGL. So anything is possbile in the future.
In my opinion the webplatform.org community should raise their voices, so Microsoft hears that we want WebGL in IE11. It's a pity that webplatform.org lists WebGL as a "hot topic" together with Microsoft as one of their key contributors on the same site. (No, it's not a pity to say WebGL is hot and to have Microsoft as a contributor at all, but it's sad that they don't show any willing to support WebGL.)