An overview on the use of microelectromechanical systems (MEMS) technologies for timing and frequency control is presented. In particular, micromechanical RF filters and reference oscillators based on recently demonstrated vibrating on-chip micromechanical resonators with Q's > 10,000 at 1.5 GHz, are described as an attractive solution to the increasing count of RF components (e.g., filters) expected to be needed by future multi-band wireless devices. With Q's this high in on-chip abundance, such devices might also enable a paradigm-shift in the design of timing and frequency control functions, where the advantages of high-Q are emphasized, rather than suppressed (e.g., due to size and cost reasons), resulting in enhanced robustness and power savings. With even more aggressive three-dimensional MEMS technologies, even higher on-chip Q's have been achieved via chip-scale atomic physics packages, which so far have achieved Q,S > 10(7) Using atomic cells measuring only 10 mm(3) in volume, consuming just 5 mW of power, all while still allowing Allan deviations down to 10(-11) at one hour.