Current practice for building on a hill involves cutting back into the hillside, sinking in caissons 30' deep or so, then building a foundation and retaining wall on which all the rest of the house can sit (usually a typical frame house on top of the crazy/heroic foundation.) Its a lot harder to do it like that, and a lot more expensive, but as far as I know, you'd never get permits for a stilt house anymore. But I don't know all the particulars. I just know some of the details, because I always wanted a house with a view.
Wow, 30 feet, that's crazy!