  Following the recent measurement of the acoustic peak by the BOOMERanG and
MAXIMA experiments in the CMB anisotropy angular power spectrum, many analyses
have found that the geometry of the Universe is very close to flat, but
slightly closed models are favoured. In this paper we will briefly review how
the CMB anisotropies depend on the curvature, explaining any assumptions we
could make and showing that this skewness towards closed models can be easily
explained by degeneracies in the cosmological parameters. While it is difficult
to give independent constraints on the cosmological constant and/or different
forms of dark energies, we will also show that combining CMB measurements with
other observational data will introduce new and tighter constraints, like
$\Omega_\Lambda > 0$ at high significance.
