OpenTop C++ Library - Multi-threading http://www.elcel.com/products/opentop/threading.html
A part cross-platform C++ library providing high-performance and portable classes for multi-threading by creating a common wrapper around Windows and POSIX threads, exposing an interface modelled on the popular Java abstractions. Cross-platform support for Java-style synchronization is provided in addition to mutexes and Unix-style condition variables. [Commercial]