SBCL targets x86, alpha, ARM, x86-64, and PPC in fact. Python doesn't actually target C, it targets a bytecode VM that's interpreted by C. which obviously is much easier to do. (there are many CL implmentations that use this approach as well eg ECL CLISP...) It just doesn't seem like Ruby or Python has the sophistication/resources yet to move their main implementations to native code, aggressively optimized compilers (yet). Which is unfortunate considering CL, Dylan and small talk got there first 30 years ago.
