Knowledge of the organization of transcription, RNA processing and transport, and the assembly of complexes such as the ribosome, spliceosome and other RNPs is essential to understanding gene expression. Over several years, the nucleolus and Cajal bodies have been examined in plants, and recently, various other sub-nuclear domains that are involved in RNA metabolism and hormonal responses have been discovered. These novel domains illustrate the complexity and subtlety of expression control and herald a new era of research on the molecular and cell biology of plant nuclei.