The following is a list of picture books that are helpful for exposing young children to the world of art.
Laurence Arnholt is the author of several books, including The Magical Garden of Monet and Camille and the Sunflowers. These are cute books about a child who meets an artist. The child differs in each book, sometimes its a boy (Camille, hey, he's French), sometimes its a girl. The illustrations are derivative of the painter's style and also feature some of the famous works.
James Mayhew also has a series of books, such as Katie and the Sunflowers and Katie Meets the Mona Lisa. Mayhew uses the same child in the various titles. Katie has adventures that involve going into the pictures she sees at the art gallery. The characters Katie meets are the subjects of the various paintings. Katie sometimes meets the artist himself, though this is only incidental to the story (as opposed to Arnholt's books where the story centers around the child meeting the artist).
You Can't Take a Balloon into the National Gallery by Jacqueline Preiss Weitzman and Robin Preiss Glasser. This is a wordless book in the format of a comic book about a girl who visits a museum and her balloon that escapes and the adventure that ensues. There are lots of pictures of works of art as well as illustrations of various parts of Washington, D.C. and events (the Cherry Blossom parade, picketing at the White House, a session of Congress, etc.) This book is especially fun for those familiar with the city. This series also includes You Can't Take a Balloon into the Metropolitan Museum (New York City) and You Can't Take a Balloon into the Museum of Fine Arts (Boston) [I may be a tad off on those titles].
Non-story Art Books:
Julie Aigner-Clark of Baby Einstein has produced a few art books such as The ABCs of Art and Master Pieces. The ABCs of Art is pretty simple, one painting per letter and a couple of simple questions about the painting. Master Pieces is an oversized board book which features only five paintings, each with several questions and answers in a lift-the-flap format. These books are fine, but I'm not a big fan of Baby Einstein, I'm especially suspicious of them since they've been acquired by Disney, that behemoth of children's entertainment. Have no doubt about it, folks, Disney is trying to steal your money and your children's minds.
Lucy Micklethwait has lots of art books. Micklethwait has a series of I Spy books about art -- I have I Spy an Alphabet in Art, this is very similar to Aigner-Clark's book, one painting per letter, but without any questions. She also offers a few other themes in her I Spy series -- I think she has I Spy with transportation in art. A Child's Book of Play in Art is an oversized book, with several paintings per page, grouped by a common theme. A fun book for an adult to peruse, though I can't say that my 4-year-old has shown any interest in it yet.