Looks like this article is over a year old, so some of the technical solutions or opinions may be a bit outdated now.

.csstransitions label {
	display: none;

Mark up your form – labels and all – and let Modernizr do the rest. Modernizr will add the .csstransitions class for modern browsers, which will then hide the labels. Internet Explorer and older browsers will still show your labels. Future versions of Internet Explorer are likely to support CSS transitions and placeholder, so everyone is happy.