The LWP spec is geared as a tool for developers to help them create multi-threaded software easier, similar to moves taken by Intel this year as multi-core processors enter the mainstream. While even the press release is a bit muddling, the spec seems to just help code be written for newer hardware:
LWP is designed to enable code to make dynamic and real-time decisions about how best to improve the performance of concurrently running tasks, using techniques such as memory organization and code layout, with very little overhead. These capabilities are particularly beneficial to runtime environments like Java and .NET, which can run multiple threads and are used to develop an increasingly large percentage of applications.
You can read the full press release at AMD's site. They cite benefits to many types of software and development frameworks, such as .NET and JVM. Obviously they have a lot of incentive to help developers write programs that take advantage of their newer CPUs.