  The decays $B^\pm\to \pi^\pm K$ and $B_d\to \pi^\mp K^\pm$ were observed by
the CLEO collaboration last year; they may play an important role to probe the
angle $\gamma$ of the unitarity triangle of the CKM matrix. After a general
parametrization of their decay amplitudes within the Standard Model, strategies
to constrain and determine the CKM angle $\gamma$ with the help of the
corresponding CP-conserving and CP-violating observables are briefly reviewed.
The theoretical accuracy of these methods is limited by certain rescattering
and electroweak penguin effects. It is emphasized that the rescattering
processes can be included in the bounds on $\gamma$ by using additional
experimental information on $B^\pm\to K^\pm K$ decays, and steps towards the
control of electroweak penguins are pointed out.
