Hogarth has put up a page that details how to disable the <marquee> tag.
If <marquee> matters to .05% of the Mozilla base, then disabling it matters to .005% of the Mozilla base.
It matters to 100% of the userbase of my copy of Mozilla, and that's what matters to me.
http://bugzilla.mozilla.org/show_bug.cgi?id=161049 is likely to happen soon. Please dear God let this be backported to 1.0.x as well.
Oh, the politics of browsing them webpages!