Doped manganites provide an interesting example of metallic ferromagnetism which occurs in a strongly correlated e g band. We analyze the magnetic interactions in manganites and show that the superexchange promotes an antiferromagnetic state accompanied by orbital ordering in the insulating LaMnO3, while double-exchange favors metallic ferromagnetism observed in doped La1 − xAxMnO3 compounds. In contrast to the common spin-Hubbard model, we find that the orbital- Hubbard model with two orbital flavours, which describes a partly filled e g band in a ferromagnetic phase, does not exhibit instabilities towards orbital ordering, but gives instead an orbital liquid state. This state explains the cubic symmetry of the spin waves observed in the ferromagnetic manganites, and the magnon stiffness constant which is proportional to the hole doping x and measures the electron correlations.