The application of all-optical time resolved techniques to nanostructured Surface Phononic Crystals (SPCs) enables the generation and detection of hypersonic frequency surface acoustic waves up to 50 GHz, with great potential for innovations in nanometrology and sensing applications. In this work, we review the advances in this field in both experiments and theory, focusing on the progress in non-destructive nanometrology of ultrathin films, on the potential for a dramatic increase in the sensitivity of mass sensors due to enhanced acoustic wave surface confinement, and on the evolution of this approach to include polymer-coated SPCs for soft material and gas sensing applications. A survey of the enabling innovative optical technologies involved is presented.