With the increasing popularity of mobile handheld devices, there is a pressing need for context-aware publish/subscribe systems over mobile environment. Publish/subscribe systems connect between information providers (publishing information in form of events) and the interested information consumers (subscribing to a particular category of events). We propose a novel approach for semantic context-aware publish/subscribe systems. Our approach replaces the traditional notion of manual subscription with a new form of automatic context-aware subscription, based on the user's location, personal preferences and interests. This has a potential of raising the quality of use in mobile publish/subscribe applications.