What's important, of course, is not just the standard exists but also that the browser supports it. Apple really did break the ground here by making Mobile Safari on iPhone quite capable, and, yes, this is the official method of recognizing iPhone suggested by Apple.

I don't keep track of developments with other mobile phones, I think Apple has really raised the bar here, so I'd expect all new small devices that pretend to have a good mobile browser to support this.

@media only screen and (max-width: 480px) {
  #sidebar, .views , #hlinks a + a {
    display: none;
  }

  #hlinks a img {
    zoom: 300%;
  }

  .question-summary {
    width: 480px !important;
  }

  .summary, .narrow .summary {
    width: 350px !important;
  }

  body {
    overflow-x: hidden;
  }

  #topbar {
    float: left !important;
  }

  #hlogo {
    zoom: 75% !important;
  }

  #hmenus .nav ul li + li {
    display: none !important; 
  }
}

This strips most of the elements, leaving the 480px wide list of questions on the main page. Similarly, one could do the questions and answers.

@hanche, true, iPhone doesn't consider itself to be a handheld indeed, but this works for iPhone since the check is for width. The check should work on modern browsers; one can also test this CSS by narrowing a browser window until it's 480px wide.

Anyway, maybe we should indeed wait for whatever the SE team solution is.

I created a feature request on meta.SE about it, but it's something we can do on our own. Are there are other volunteers to try it (my wifi is currently broken, so no iPod goodness for me for a while)?