In this expository talk, we explain results of Leclerc and Thibon connecting certain Kazhdan-Lusztig polynomials to q-analogues of Littlewood-Richardson coefficients. This connection has been used by Haiman-Haglund-Loehr-Remmel-Ulyanov to prove Schur positivity of a conjectural formula for the Frobenius series of the diagonal coinvariants of the symmetric group. The main tools I will introduce in this talk are ribbon tableaux, the spin statistic on them, and the Fock space representation of the affine symmetric group. The material on Kazhdan-Lusztig polynomials covered in my talk from the fall, while very useful background, is not a prerequisite for this talk.