This article discusses the current market push to 64-bit computing, and how Linux's flexability and portability make it an ideal choice for whatever new hardware platform is chosen.
While the title emphasizes Linux, the article itself mainly delves into 64-bit computing, including the current players, the history and future directions of 64-bit computing, and a great comparison of the different 64-bit architectures available. If you haven't read much on this subject yet, this is a great intro.