If you read French, you have to read this beautiful letter written by a leading figure in the world of bilingualism, François Grosjean. He was one of the first author I ever read when I was studying this topic.
This letter is a little more personal but summarises bilingualism so well and is well informed!
It just reminds me how great a gift I am giving my daughter.
Edited to say that he has now published the same letter in English here.