Opera 9 handles this pretty damn well.
Safari 2 and Firefox 2 do not support this out of the box.
Microsoft is ignoring this
BTW, the WF2 implementation for IE, although unfinished, does work. It implements all of the <input> types (except datetime), the <datalist> element, the <output> element, validation and ValidityState objects, multiple forms and the new events. The implementation looks and feels exactly like a native Windows implementation. We even mimic the user's current XP theme. Download it and try it. I would appreciate any feedback either privately or on this list.
--Dean Edwards on the WHAT WG List, Monday, 05 Feb 2007 20:30:03