Ah, the joys of having a 3 year old.
I tried the "soft cloth, water, and mild soap" that Sony recommends, but it did nothing.
Crayola has whole document on cleaning crayons and other of their products off of things. They recommend WD-40 for cleaning crayons off of plastics.
So I tried it lightly in a small spot in the corner, and it seemed to worked great, so I went for it. Sprayed it on one of those Viva cloth-like paper-towels (since I didn't have any other soft cloths around), then lightly wiped over (and up off) the surface. The crayon seemed to dissolve almost on contact.
There was a slight residue left, so I used water and the Viva towel to dampen it, then a dry one to dry it. To my eyes it looks great.
Of course YMMV. (i.e. don't blame me if you try it and it messes something up! =) Hope that helps somebody.