A few more hints, complimentary to Robin's ones about Ajax:
End user doc on how to setup a workflow event :
http://ez.no/ezpublish/documentation/building_an_ez_publish_site/the_guestbook/creating_a_workflow http://ez.no/ezpublish/documentation/building_an_ez_publish_site/the_guestbook/connecting_the_workflow_to_a_trigger_function
Online developer documentation about workflows : http://ez.no/ezpublish/documentation/development/extensions/workflow_events (navigate the mini tutorial through the right-hand menu where "workflow events" is in bold)
Hope that helps
let us know how it goes, Cheers!
--
Nicolas Pastorino
Director Community - eZ
Member of the Community Project Board