Every "contender" browser I've tried (konqueror, IE, Opera, Netscape 4.x-6.x, Mozilla, I'm kind of a collector) supports it. W3 recommends it's use here. It's safe to say that those that care to use it would probably have a browser that supports it. This works for ANY form element too- The trick is choosing "alt-key" combinations that aren't already taken by the browser or the OS.

-Any sufficiently advanced technology is
indistinguishable from doubletalk.