  The decays B_{d,s}^0 --> K^{(*)} K-bar^{(*)} can be used to measure the angle
alpha of the CKM unitarity triangle. The theoretical error from SU(3) breaking
is expected to be small, so that the determination of alpha is clean. Moreover,
since B_{d,s}^0 --> K^{(*)} K-bar^{(*)} are pure penguin decays, they are
particularly sensitive to the presence of new physics
