I am going back over a recent project sorting out accessibility issues and was making sure all form elements had labels. Putting the label text into a tag caused a problem with some kludgy code I had written before.
Basically, if you have a radio button and its label:
<label for="zone_r1"><input type="radio" name="zone" id="zone_r1" value="NY" />New York</label>
<input id="NY" type="radio" name="zone" value="NY" /><span id="nyTXT">New York</span>
works for me