Multi-input multi-output (MIMO) radar is an emerging technology that has significant potential for advancing the state-of-the-art of modern radar. A MIMO radar deployed on a moving platform, with the signals coherently combined from pulse to pulse for imaging, is termed as MIMO synthetic aperture radar (SAR). Potential benefits of MIMO SAR include significant reduction in the system pulse repetition frequency, smaller losses when observing stationary and low-velocity targets, reduction of shadowing effects for 3D imaging, and realization of a synergistic MIMO SAR and ground moving target indication capability. In this paper, we provide a detailed review of the MIMO SAR technology, discuss its attributes, and highlight its potential for area surveillance, particularly in urban environments with dynamic complex terrains.