The Optimus keyboards  by Art. Lebedev Studio have been around for a while but they've always been prohibitively expensive. While this keyboard doesn't have color in the displays, it's actually affordable.
Another similar product is the Razer DeathStalker Ultimate  keyboard, but only 10 if its buttons have programmable displays.
I wonder why Razer (or anyone else) haven't made a standalone keyboard that followed the approach they took with their Switchblade  concept. They put transparent keys over a large lcd panel. It's much cheaper than putting a tiny lcd display inside each key.
That could be from a number of different effects, ranging from render parameters (of either the minions, the color sample or both) to optical ilussions. Also, they may already have a similar colour and chose to name "minion yellow" a new shade, which still resembles the minion's iconic colour.