  I recently proposed the "reheating-volume" (RV) prescription as a possible
solution to the measure problem in "multiverse" cosmology. The goal of this
work is to extend the RV measure to scenarios involving bubble nucleation, such
as the string theory landscape. In the spirit of the RV prescription, I propose
to calculate the distribution of observable quantities in a landscape that is
conditioned in probability to nucleate a finite total number of bubbles to the
future of an initial bubble. A general formula for the relative number of
bubbles of different types can be derived. I show that the RV measure is
well-defined and independent of the choice of the initial bubble type, as long
as that type supports further bubble nucleation. Applying the RV measure to a
generic landscape, I find that the abundance of Boltzmann brains is always
negligibly small compared with the abundance of ordinary observers in the
bubbles of the same type. As an illustration, I present explicit results for a
toy landscape containing four vacuum states and for landscapes with a single
high-energy vacuum and a large number of low-energy vacua.
