Visit http://slides.html5rocks.com/#speech-input and hover over the microphone widget. Notice that the i-beam cursor is (appropriately) used for most of the input, but the microphone icon uses the pointer cursor. It seems like the microphone should instead use the hand cursor to indicate that it is clickable (just like a link or button would appear).
The <input type='search'> field has a clear button (displays an 'x' image when the field has text) and that uses the default arrow cursor.. same goes for other clickable buttons. There are some websites which override the cursor to show the hand for clickable buttons, these are not the default behavior. So no change required here.