The emergence of location-aware mobile social networking applications (SNAs) has gained considerable prominence in ubiquitous computing. However, the weak designs of privacy protection result in more potential risks that users have to face. This paper presents a deep insight into the designs of privacy protection, especially from the perspective of location privacy. Three main potential risks and some necessary privacy-related functionality in current applications are analyzed and summarized. And with respect to the risks and weak protection methods, we propose the designs of privacy protection in LaMOC which is a location-aware mobile cooperation system developed by us. The designs include both the policy-based mechanisms and computational approaches to protect users' location privacy. Policy-based mechanisms enable users to fully control their locations disclosure while computational approaches can protect users' real locations from malicious attackers. The designs provide a reasonable level of privacy protection in location-aware mobile SNAs to some extent.