If you want to do browser-based 3D rendering, WebGL looks great but simply isn't supported in IE. Since the only other real option for browser-based 3D is to use a plugin, then it seems like Chrome Frame is a viable alternative... IE users still have to install the plugin/addon/extension but other users on FF/Chrome do not need to.
In a corporate environment we might expect installing browser-addons to be hard to get permission for... but as I say on IE you're going to have to install some sort of plugin regardless, whether it's generic like Chrome Frame or specific like Unity3D or your own bespoke plugin.
Does this seem reasonable, that we can simply drop IE support for this kind of specialist app and let Chrome Frame automatically run on IE when needed?