A Pattern Language for Distributed Computing, the fourth volume in the Pattern-Oriented Software Architecture (POSA) series, has been published by Wiley. It is coauthored by Frank Buschmann (past ACCU conference speaker), Kevlin Henney (long-standing ACCU member, ACCU conference speaker and Overload contributor) and Doug Schmidt. POSA4 offers a comprehensive guide to the architecture of distributed systems, expressing the key design decisions and trade-offs through patterns.
The same authors have also written On Patterns and Pattern Languages, the fifth POSA volume, which was launched at the 2007 ACCU conference. POSA5 provides readers with a comprehensive view of key pattern concepts, how they interrelate and how they support software developers and software development, building up from standalone patterns, through various forms of pattern relationship, to the concept and realisation of pattern languages.
More details and sample chapters can be found here:
http://eu.wiley.com/WileyCDA/WileyTitle/productCd-0470059028.html
http://eu.wiley.com/WileyCDA/WileyTitle/productCd-0471486485.html