JJ links to a presentation from Paul Prescod about resource-oriented as opposed to service-oriented architectures. I find the argument convincing that the difference between SOA and ROA (REST) is more about whether there are services at all than about what kind of interface (uniform or not) is exposed.
The comparison is an interesting one. It is something we have thought a lot about at 1060. I have tried to summarize the principles of each and compare them to the sum of principles embodied in NetKernel in this page: http://www.1060.org/netkernel/