But now, Joe's sent us his new version, called Ringtonator Studio, and he tells us that not only will it accept any Quicktime formats, but it will also let you crop your tunes, and then translate them directly into ringtones. And, he says over on his blog, it will work with iTunes 7.4.2. That's probably a YMMV thing, but if you're really frustrated that you haven't found a way to get around Apple's lockout, it's worth a try.
And no guarantee, of course, that any ringtones made won't disappear with 7.4.3. But kudos to Joe for putting this all together, and doing his part in the fight to give us control over our ringtones.