IE (and pretty much every browser as far as I can tell) has always supported DELETE in XMLHttpRequests (or MSXML as the case may be). Presumably Rick is talking about DELETE working in <form>s.
My code (I've tried it with both upper-case and lower-case DELETE):
<form action="http://example.com" method="DELETE">
<input type="submit" />
</form>I would reference when it was added, but since it's a working draft spec, it's been removed and I can't find the original addition date - but I believe it to be mid to late 2009.
[1] http://www.w3.org/TR/2010/WD-html5-diff-20101019/#changes-20...