That works nicely for checkboxes, but sometimes you want the form field and label to be in (say) different cells of a table row or something.

labels should always be to the right of the checkbox/radio controls. never nest them. nesting is ok for other form controls in some instances, but you'll run into issues with various screen readers if you apply the for attribute while nesting. on that note, always nest when possible; the ux benefits make it crazy not to take advantage of it.

You still have to do the complementary for= and id=, but I am also a proponent of nesting, though I have not solicited public opinion on it until just now.

Here is how I started doing it:

<label for=abc><input type=checkbox id=abc ...> display alphabet<label>