  We propose a new method for measuring the CKM phase gamma using the partial
rates for CP-tagged Bs decays. Such an experiment could be performed at a very
high luminosity symmetric e+e- collider operating at the Upsilon(5S) resonance,
where the Bs-Bsbar state is produced in a state of definite CP. We also discuss
CP-tagging in the Bd system at the Upsilon(4S), where a time-dependent analysis
is required to compensate for the anticipated large CP violation in Bd-Bdbar
mixing.
