iBooks alternate language dictionaries?
This has changed in iOS7. Look up a word, at the definition UI push "Manage" in the bottom left, and a list of foreign dictionaries comes up:

English, Apple, Oxford-EN, Spanish, Korean, KOR-EN, JP-EN, Italian, German, French, Dutch, Simplified CN, SCN-EN, and Japanese.

Any &amp; all can be downloaded from inside this "Manage" screen, and the definitions will trail (as things do on the OSX side with Dictionary.app).