Wes Kendall from University of Tennessee, Knoxville has produced a website showing how to code in MPI, including installing an Amazon EC2 cluster. For portability, the site content is also available as a Kindle ebook for only US$5.
This is not Linux-related, at all, but it is in keeping with my work in high performance computing. One Michael McMahon built an Apple IIe-based parallel computer in 2008. His second, in fact. He calls it the Apple Crate II. He also created the operating system and the message-passing programming language (an extension of Applesoft BASIC). [Via BoingBoing.]