  Various features of spin-polarized Fermi gases confined in harmonic traps are
discussed, taking into account possible perspectives of experimental
measurements. The mechanism of the expansion of the gas is explicitly
investigated and compared with the one of an interacting Bose gas. The role of
interactions on the equilibrium and non equilibrium behaviour of the fermionic
component in Fermi-Bose mixtures is discussed. Special emphasis is given to the
case of potassium isotopes mixtures.
