Of course, because it uses CPAN, it's not really just 121 lines. And, actually, I didn't even write it. But the point is that a short time after I wondered "gee, is there a way to import Gravatars to Gmail?", I found a Perl program to do the job.
In this case, it turned out to be a pre-module experiment by prolific CPAN author Tatsuhiko Miyagawa. Through a Google search, I found his google-contacts-gravatar code on github.com, cloned it, installed its dependencies, and minutes later had imported all gravatars matching my contacts list.
Awesome! Thank you Miyagawa, and thank you Perl.