Based on feedback from Microsoft the algorithm used by responseText now takes the potential BOM of the entity body into account. Please let me know if you spot any issues with this:
http://dev.w3.org/cvsweb/~checkout~/2006/webapi/XMLHttpRequest/Overview.html?content-type=text/html;%20charset=utf-8#text-response-entity-body -- Anne van Kesteren <http://annevankesteren.nl/> <http://www.opera.com/>
