Even if the GIL is not a big deal in many cases, it remains a factor worth considering in designing and deploying applications. If I were running a single instance of a multithreaded application on an SMP box and had limited hardware resources, I'd want to be aware that one CPU would be underutilized and think about what else I should run on it, too. And if I were writing a Python application to run on a mosix cluster, the GIL would force me away from a threaded architecture, because Python threads won't migrate. But the fact that the GIL matters in some situations doesn't mean that Python sucks, or that applications that don't scale to SMP suck. It isn't unheard of for OSes -- damned good OSes, like Linux -- to have difficulty with SMP, too.