If you're working on a POD document and you want to upload it as a GitHub gist, just add the following to the top:

#!/usr/bin/env perl
use App::gist;
@ARGV = $0;
App::gist->run;
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... and mark the POD file as executable. Then run it. (Many programmers' text editors have a built-in command or hotkey to execute the current file.) Yay, it's uploaded to GitHub as a gist. This should give you a numeric gist identifier. Change the third line to:

@ARGV = ('-u', 412345, $0);  # or whatever identifier
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Now executing the file will update the existing gist in place.

Yet another reason to use POD over another markup language. :-)