For inputs of type text and checkbox, and select controls, the enter key is blocked and the next visible, non-disabled control is focused, unless it is the last control in the form, in which case the enter key is passed through. Tested in IE6 for Windows XP SP2 and in Firefox 2.0.0.7. Fx's JavaScript console collects permission errors in testing when the event.target control is of type text, but this does not seem to inhibit the desired function.
To discuss, go here: Mozillazine Forums Thread. Last updated 1 October 2007: Jefferson Scher