In the home stretch now. The little "L" shaped pieces being glued on serve several purposes:

(1) They conceal the end grain of the plywood; but much more importantly,
(2) They add strength to the shelves preventing bending under heavy loads, and
(3) They provide extra visual "weight" to the shelves balancing the overall look.

The edges of these will be eased with a 1/8 inch round over before finish is applied.