This post comes in response to a question on the ServiceNow forums asking if it is possible to change the label of a field dynamically based on some record criteria (such as record type). I've just written a function that makes it very simple to change a field label's text, color and font weight. See the full details at SNCGuru.

http://www.servicenowguru.com/system-ui/ui-scripts-system-ui/modifying-label-form-fields-client-scripts/