Update:
With HTML5 running on pretty much all platforms, you want to use the placeholder attribute instead of any sort of tricks to place a label inside your input widgets.
This is done like this:
<input type="text" placeholder="Phone Number"/>
This example will show "Phone Number" inside the input box until the user types some text in that box.
You can test with the box right here. This is just that one <input .../> tag I placed in my page HTML. (It is not in a form, but the widget itself will work as expected.)
For additional details, I ...
