There was some thought of using it to represent dimension for Vectors, Matrices, and Fixed Arrays:
let vec3 : Int[3] = ...
let matrix : Double[2][2] = ...
of course there is also the idea of:
let vec3 : Int x 3 = ...
let matrix : Double x 2 x 2 = ...
I do find the first much easier to read, but that may just be my C background...