Does everything now make (anti)sense?

The data generated by the FANTOM (Functional Annotation of Mouse) consortium, Compugen and Affymetrix have collectively provided evidence that most of the mammalian genomes are actively transcribed. The emergence of an antisense RNA world brings new practical complexities to the study and detection of gene expression. However, we also need to address the fundamental questions regarding the functional importance of these molecules. In this brief paper, we focus on non-coding natural antisense transcription, as it appears to be a potentially powerful mechanism for extending the complexity of the protein coding genome, which is currently unable to explain inter-species diversification.