  Studies of cluster X-ray scaling relations have led to suggestions that
non-gravitational processes, e.g., radiative cooling and/or "preheating", have
significantly modified the entropy of the intracluster medium (ICM). For the
first time, we test this hypothesis through a comparison of predicted thermal
Sunyaev-Zeldovich (SZ) effect scaling relations with available data from the
literature. One of the relations that we explore, in principle, depends solely
on SZ effect observations, thus offering an X-ray independent probe of the ICM.
A detailed comparison of the theoretical relations with the largest compilation
of high redshift SZ effect data to date indicates that the presence of an
entropy floor is favored by the data. Furthermore, the inferred level of that
floor, 300 keV cm^2 or higher, is comparable to that found in studies of X-ray
scaling relations of nearby massive clusters. Thus, we find no evidence for
significant evolution of the entropy floor out to z = 0.7. We further
demonstrate that the high quality data to be obtained from the upcoming
Sunyaev-Zeldovich Array (SZA) and the (soon-to-be) upgraded Owens Valley Radio
Observatory (OVRO) array will open powerful new windows into the properties of
the ICM. Specifically, the new measurements will allow for accurate
measurements of the ICM entropy for even the most distant galaxy clusters.
