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ICU is International Components for Unicode.
I've requested this via IRC and mail a few times back but still no progress. I've just tried deploying an application that uses my icu-wordsplit package to no avail. (build fails since there is no libicu there.)
I believe this is important for any apps which requires international support, sooner or later you wil run into libicu and that is why I am requesting that nodejitsu adds it instead of embedding the whole of icu into my application.
We should be able to support this without much trouble, but we'll have to investigate first. Thanks for bringing it to our attention - this is a simple and useful feature, and we'll add it as best we can.
Internal tickets indicate this was added to our platform some time ago. Feel free to test it out!