Goo Gle released its Protocol Buffers project as Open Source. Binary serialization for RPC.
Dare Obasanjo notes that such things can make sense when you control both endpoints and can afford some tighter coupling. Saying it's a different Con Text than Steve Vinoski's arguments against RPC (in favor of Re ST).
Bill De Hora considers options for passing control messages among servers: he still thinks binary objects are a bad idea, even if you use an RPC model (1 of his 3 options is RPC, the others are Re ST/HTTP and XMPP Pub Sub).
De Witt Clinton comments that Re ST is really only good for documents and collections: RPC is not state exchange.
Sept'2008 update: Roy Fielding notes an Os Con session arguing that XMPP-based Pub Sub scales better than Re ST, and argues on the basis of both tech and economics.