  The determination of the angle $\gamma$ of the unitarity triangle of the CKM
matrix is regarded as a challenge for future $B$-physics experiments. In this
context, the decays $B^\pm\to \pi^\pm K$ and $B_d\to\pi^\mp K^\pm$, which were
observed by the CLEO collaboration last year, received a lot of interest in the
literature. After a general parametrization of their decay amplitudes,
strategies to constrain and determine the CKM angle $\gamma$ with the help of
the corresponding observables are 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.
Moreover, strategies to probe the CKM angle $\gamma$ with the help of $B_s\to
K\bar{K}$ decays are briefly discussed.
