You are right many applications of MEMS Mic array are under development in many different areas, in the filed of mechanical engineering, environmental science, medical electronics etc. Soon many products will be in the market using MEMS Mic arrays. Although these Mics are still not being tried as conventional microphones that are used in live performances.
Beside smartphones, tablets all use MEMS microphones, also many PCs are switching over because they can locate mutiple MEMS in the bezel for noise cancelling and beam stearing. Apple's smart watch due this fall will use MEMS microphones also video camera, still cameras and digital recorders are all moving to MEMS mics. For the next generation, wearables will use MEMS mics and portable medical devices and the list goes on.