Well, many of the concepts of the lisp machine are extremely relevant to the current design problems of today's CPUs, primarily around security and privacy. The continuing disaster promulgated on the world by languages such as C can only be solved by enforcing type safety and bounds checking in hardware. There continues to be progress in making these easier and more efficient to implement. I'd suggest looking at the SAFE architecture papers, especially the low-fat pointer paper: http://www.crash-safe.org/papers.html