Sameer Tyagi has written an excellent article about developing document-based Web Service in Java for the Sun website. The detailed discussion of doc/lit vs. rpc/enc might have been shortened to “use doc/lit and forget about the rest” — I can think of no reason other than taking over existing code for anybody deciding to use rpc/enc. Some of the possible solutions are a little absurd, but for the sake of completeness, I think this is forgivable . The only thing I really miss is a reference to WS-ReliableMessaging (or WS-MessageDelivery if you prefer) in the last section (which deals with asynchronous processing).
Anyway, very good reading, highly recommended.