Gas separation is an application area for membrane technology with a long history. As a consequence, several membrane-based gas separations are now mature, although there is still a steady improvement in performance of membranes, and membrane functionalities. During the last decade, membrane gas separation had a new impulse mainly due to emerging environmental application, and the integration of energy production/consumption with environmental concerns. This resulted in a second wave of innovations on all levels, from membrane development to process engineering. This perspective outlines the recent trends in membrane applications related to gas separation, based on the history of scientific research in membrane gas separation, and with reference to competing technologies such as cryogenic distillation, absorption, and adsorption on zeolites or other materials. In addition, the potential of hybrid technologies and newly emerging membrane-based technologies, such as membrane contactors, is probed.