I just released an update which includes a sample application. The
plug-in is available at http://railsrtv.rubyforge.org
The RTV plug-in uses AJAX to validate form data against a model in
real-time. AJAX requests are made as the user is filling in form
fields. The form data is then validated against a model on the
the HTML document. This enables you to mark form fields as
valid/invalid using CSS.