Grand Central is the latest Apple trademark. No, it has nothing to do with the Google service of the same name or, for that matter, the famous train station. Grand Central is the technique used by Apple's forthcoming Mac OS X Snow Leopard to handle multiple processing cores.
As we gradually migrate from computers with a single powerful computing resource to many resources, managing work across those resources becomes far more important, and that's exactly what Grand Central is intended to improve. In short, it will make OS X smarter about assigning tasks to processors.
Also included in its responsibilities is Apple's Open Computing Language (OpenCL), which was recently published as a public specification. OpenCL is the technology that's allowing general computing tasks to leverage the power in today's video cards, which often goes to waste merely drawing pretty pictures. Every version of OS X seems to promise better multiple processor usage, so we'll have to wait and see if this trademark delivers, or if its another marketing tool.