Over the last decade, our picture of RNA as a mere information carrier has changed dramatically. Since the discovery of microRNAs and siRNAs (see e.g. [1,2] for a recent reviews), small noncoding RNAs have been recognized as key regulators in gene expression. Both computational surveys, e.g. [3-7] and experimental data [8-11] now provide compelling evidence that non-protein-coding transcripts are a common phenomenon. Indeed, at least in higher eukaryotes, the complexity of the non-coding RNome appears to be comparable with the complexity of the proteome. This extensive inventory of non-coding RNAs has been implicated in diverse mechanisms of gene regulation, see e.g. [12-16] for reviews.