If there's anything the GIS mainstream knows about REST, it's that REST is simpler and more lightweight than SOAP, "Web Services", or the OGC's service architecture. This notion is erroneous, and it's irresponsible to propagate it.
Bill de hÓra makes the distinction between disciplined and simple:
REST is not that simple; you can fit the basics into a few slides, but its purpose is to induce simplicity into the right places, not [to] be simple.
He's also compiled a great list of XMPP links.