JSF 2.0 Page Actions

I have been trying to find further information about a feature promised in JSF 2.0 called "page actions", which was implemented based on a similar feature in Seam. The idea behind this (new) feature of JSF is to enable an action to be specified on a GET before a page is displayed...so for example you might want to preload data before a page is rendered, enabling you to trap errors before the rendering process. I have the JavaServer Faces 2.0: The Complete Reference book which is quite good (and has a far better index than the previous edition), but it doesn't seem to have any information about this feature. Can anyone point me at a web resource that describes how to implement it? Or alternatively, a web resource that indicates that the feature never made it into the final release?

Thanks in advance.