Ed,

It's part of the HTML 3.2 and 4.0 specs so I'd assume nearly every browser out there supports it. The 4.0 spec even mentions that agents can use the text for things like speech rendering.

>Hey, thanks. I do see the tooltip. I was wondering whether that could be done with a browser.
>
>Now is that a DHTML feature? I'm using IE 4.0 on this computer so clearly it works with that. Do you know what browsers it does or doesn't work with?