  The article discusses the properties of time evolution of wave packets in a
few systems. Dynamics of wave packet motion for Rydberg atoms with the
hierarchy of collapses and revivals is briefly reviewed. The main part of the
paper focuses on the new mechanism of quantum reccurrences in wave packet
dynamics. This mechanism can occur (in principle) in any physical system with
strong enough spin-orbit interaction. We discuss here the SPIN_ORBIT PENDULUM
effect that consists in different motions of subpackets possessing different
spin fields and results in oscillations of a fraction of average angular
momentum between spin and ordinary subspaces. The evolution of localized wave
packet into toroidal objects and backwards (for other class of initial
conditions) is also subject to discussion.
