A week and a half ago I wondered what IE 7 would do if you would have comment before the
doctype. IE 6 is thrown in quirks mode when you have got anything before the
doctype. John A. Bilicki commented on the IEBlog that it would throw IE 7 in quirks as well.
There is a new post on IEBlog on the <?xml> prolog, strict mode, and XHTML in IE by Chris Wilson where he writes:
I realized as I read through the comments to my last blog post that I forgot to mention one important item that was in my presentation. We have fixed the DOCTYPE switch so it will skip an XML prolog, so that valid XHTML can be handled in strict compliance mode rather than quirks mode.