Gruber uses the word 'Raconteur' in his Twitter Bio. I didn't know what the word meant, I looked it up. Well, for me, he is truly a raconteur (along with Joel).
This function has been there at least since Leopard and the old shortcut still works: cmd+shift+D. Saddens me that Chrome still doesn't support it at all, and it breaks in Safari when web-fonts are involved.
With additional dictionaries, this feature is pure gold for language learners.
RIP, Steve.