I've been reading this blog over at sitepoint about Who Gets Rest by PHP heavy Harry Fuecks. It is a fairly link-heavy top level view of what REST is.
Its nice to see more the PHP guys get into REST, as far as PHP guys go, Harry is pretty Heavy. What harry has to say about URI naming schemes (especially in the comment section) really helped to gel a very important part of REST for me.
He comments that Harry's ideas about seperation of "tools" from the resources they work with is a very appealing idea, and one that would allow much more flexibility in PHP applications.