I was pretty much going to say what Paul said about grouping radio buttons and a label needing a unique identifier to attach itself to, hence the id attribute.

Also, browsers should use the text enclosed by the label element to increase the clickable area for the associated form input. Try it out on your comments form. You'll see that clicking where it says ‘name' doesn't bring focus to the name input - the content of the for attribute doesn't match the input id. However, click where it says ‘Remember' and the checkbox's state toggles. Click ‘Message' and the textarea gains focus.

I sometimes wrap a form input in the label element as well for explicit labeling, mainly because I find it easier to style.

IE7 finally brings support for CSS2 attribute selectors to Internet Explorer - yay! - but I find I use it very little.