  We present a new theoretical framework for the study of $B\to X_u \ell \nu$
decays, which includes all known perturbative and non-perturbative
contributions and a description of leading and subleading Fermi motion effects.
The perturbative and non-perturbative regimes are separated by a ``hard''
Wilsonian cutoff $\mu \sim 1$ GeV. We bring into focus some problems related to
the high $q^2$ region and to Weak Annihilation effects. We provide estimates of
the CKM parameter $|V_{ub}|$ using the described framework and discuss the
related theoretical uncertainty.
