Ferromagnetism exhibits exciting novel phenomena when the system size is shrunk to submicron scale. Especially interesting are heterostructures with ferromagnetic and nonmagnetic regions combined in multilayer cake-like structures. I will briefly review the field of mesoscopic magnetoelectronics, where such structures are incorporated in Ohmic circuits, focusing on the scattering- matrix approach. The field received its first significant boost with the experimental discovery of giant magnetoresistance, some 20 years ago. Ten years later, theoretical prediction of current- driven magnetic instabilities, with subsequent experimental confirmation, ignited interest in ferromagnetic dynamics in hybrid nanostructures. Since then, many aspects of magnetization dynamics, such as current-driven reversal, stable precessional states, spin pumping, microwave emission, low- and high-frequency magnetization noise have been extensively explored. A large body of fascinating experiments offer a broad basis for theoretical exploration, but the number of open questions has only been growing in recent years. I will describe several insightful experiments, discuss theoretical progress in understanding nanomagnet dynamics, and briefly discuss some theoretical proposals for spintronic applications.