Greg Laden points out a recently published paper in PNAS that gives credence to the theory that non-coding RNA has specific function. The work identified 849 ncRNAs (of 1,328 examined) that are expressed in the adult mouse brain, the majority of which they also found were associated with and expressed in specific regions, cell types, or cellular compartments. He's blasted here and here for his supposed naivety, but he maintains that the "paper is interesting and the evidence for ncRNA having some function is reasonable."