Sam Ruby, author of "RESTful Web Services" seems to come out against the use of HTTP PUT for partial updates: http://intertwingly.net/blog/2008/02/15/Embrace-Extend-then-Innovate
What isn't clear is how partial updates should take place. As I commented near the bottom of his blog, it isn't clear how using HTTP PATCH is any better than using a "patch document" against HTTP PUT.
It is worth noting that although Sam comes out against misusing HTTP PUT he doesn't seem to advocate the use of HTTP PATCH either.
How should one submit RESTful partial updates?