I wrote a doc in TurboGears doc site: Wrap AJAX operation in Widgets, which demonstrates how to use the widget to do basic AJAX operation as Rails 'link_to_remote' helper.
The RemoteLink widget works differ from Rails 'link_to_remote' helper. It's simple, pure python(while you use it) and fully 'optional'! 'Optional' means if you remove the widget, your site still functional. Thanks to the mochikit cool functions :-)