One interesting phenomenon is the how Ruby and Rails are mostly in parallel worlds. It can't just be a language barrier. There are lots of initiatives like JRuby and Rubinius that are more or less ignored by the Ruby Core team.

With all the Ruby enthusiasts outside of Japan, it seems unnatural that most of the core commiters are still Japanese.

http://svn.ruby-lang.org/cgi-bin/viewvc.cgi/trunk/