I review the recent progress in computing inclusive B decay widths and spectra and its implications
on the interpretation of measurements from the B factories. I discuss the inclusive charmless
semileptonic decay, ¯B ! Xul¯ , which provides the most robust determination of the CKM parameter
|Vub|, and the rare radiative decay, ¯B ! Xs
, which constrains flavor violation beyond the
Standard Model. I demonstrate that precise predictions for the experimentally–relevant branching
fractions can be derived from resummed perturbation theory and explain the way in which the
resummation further provides guidance in parametrizing non-perturbative Fermi–motion effects.
Finally I address the comparison between theory and data and discuss future prospects
