This work explores the potential benefits of orientation awareness in wireless systems in the context of source localization. Precise and reliable inertial measurement units have become a standard feature on almost all smartphones available today, and they are becoming increasingly popular for other devices as well. The measurements provided by such sensors can be employed as side information in a number of application scenarios, including inference. Indeed, orientation information combined with the asymmetry of antenna radiation patterns can lead to substantial performance gains in localization algorithms. This article focuses on source localization based on received signal strength. Improvements are assessed from both a theoretical and an experimental perspective. Reported findings offer supporting evidence to the claim that orientation-awareness can improve performance in a significant manner.