They're not an official product, but are one an extensive range of stickers available from the Portuguese company Moon WallStickers.
The stickers are printed with an illustration, rather than a photograph, of Lego-style bricks in an array of bright colours and brick sizes. They can be applied to any sleek or clean surface (meaning that it's not only your stairs that might get a make-over) and are heat and water resistant. Each pack comes with 49 tile stickers.
Prices start at £71.55.
Order them through Bouf.