Internet Explorer 10 supports the number input. This is evident from a cursory examination of their documentation, as well as an attempt to use it within the browser itself. For example, attempting to place a letter in a number input will result in the value being cleared when the control loses focus.
You can also feature-detect support for number by programmatically doing the aforementioned test:
// Create the element
var element = document.createElement( "input" );
// Give it the number property and invalid contents
element.type = "number";
element.value = "qwerty";
// Value should be empty
alert( element.value ? "Not Supported" : "Supported" );
Run this test: http://jsfiddle.net/VAZwT/
It may very well be that you’re equating progressively-enhanced UI (the spinners) with support for the control itself. I’ve seen this confuse a few people already. Some browsers augment supplement the number input with additional controls, but this is not (to my knowledge) a requirement for support.
A few simple tests for min, max, and step on jsfiddle: http://jsfiddle.net/sDVK4/show/