Diffusion of penetrants through polymer thin films is important in a variety of applications ranging from microelectronics to gas separations. Recent experiments have shown that the diffusion behavior of polymer ultrathin films appears to be anomolous with strong dependencies on the polymer film thickness and molecular weight. In an attempt to understand the origin of these phenomena, we have recently investigates the aging behavior of polymer ultrathin films as a function of film thickness and polymer molecular weight. This presentation will provide a summary of these recent experiments and the insight that they have shed on the possible origins of the anomalous diffusion behavior in such systems.