The problem is it starts breaking down at around 250C, and if you leave a pan on a stove it can easily get above that temperature. The chemicals it breaks down into are known neurotoxins, and are especially lethal to birds.
In Europe (especially Italy where I believe Teflon is banned in cookware) ceramic coatings are becoming the standard for non-stick cookware.
I hope the silicon stuff is OK; I prefer that as it's point of thermal breakdown is way past anything I want in my kitchen anyway (aside from direct open flames which I don't currently use but know some cooking does).
I also prefer the ceramic linings, since those are more likely to be OK in my mostly uneducated opinion. (However the type of material is different, and hopefully less likely to leach).
In Europe (especially Italy where I believe Teflon is banned in cookware) ceramic coatings are becoming the standard for non-stick cookware.