MZ Scheme links trivially to C libraries. I would think that anyone who uses Arc would use this facility heavily. Now whether there exists a C library to do exactly what you want is a different question. And I know this might be heretical here, but ROR is hardly the great time saver the fanboys make it out to be when you count in issues like deployment and doing non standard things with it. (Don't get me wrong, it is a good framework, but it is hardly a magic wand and neither is it very unique - Wicket + scala comes very close to ROR in productivity for example)
PS: How long do you think it would take before people hack up a virtual machine or C code emitter? I, for one would do exactly this if I planned to use it in my startup. It isn't that hard (Ruby's recursive descent sloooww interpreter still powers all those RoR sites, minus the vanishingly few ones in JRuby.)
So no, 'trivial' C linking not actually a silver bullet making everything hunky-dorey with respect to lack of libraries. Python has a significant advantage in that it's popular enough for many people to have already gone through the Pythonification process for most important libraries, and have also open-sourced their Pythonification layers.