tchrist seems pretty knowledgeable on unicode issues. He even did 3 talks at OSCON on the topic. My takeaway wasthat the best language for dealing with Unicode was Perl, and Ruby was the second best.
Ruby 1.9 doesn't even offer Unicode case folding, so from a practical standpoint working with Unicode text is a PITA with Ruby unless you use third party libraries.
Ruby source can include constants, variables, etc. with Unicode (or other character set) symbols, which is very cool but for Unicode text processing I've found Ruby to be frustratingly lacking.
http://code.activestate.com/lists/perl5-porters/166738/
Hmmm... According to that email he says that Java is second, but in his first talk he did say that Ruby (1.9+) was second in his mind (and he seemed to be visibily frustrated with Java's Unicode support).