I started playing with this yesterday. It might make for a good alternative to canvas. At least from a compatibility standpoint.

Internet Explorer doesn't have native support for canvas or svg, which is why Excanvas and Raphael fall back on vml to provide canvas and svg-like support, respectively.

Canvas and vml really aren't a good match, though. Canvas is stateless, whereas both vml and svg insert objects into the DOM. It's this mismatch that really kills Excanvas' performance when rendering any kind of animation.