A smart space enhances a networked computing environment by enabling information sharing for a multitude of local digital devices and global resources from the Internet. We consider the M3 architecture (multi-device, multi-vendor, multidomain) for creating smart spaces, which integrates technologies from two innovative concepts: the Semantic Web and the Internet of Things. Our research focus is on analyses of the capabilities of Smart-M3 platform, which provides software implementations for such a central element of an M3 smart space as Semantic Information Broker (SIB). The paper presents a state-of-the-art and contributes our systematized vision on the SIB design and implementation. The analyzed open source SIB implementations include the original Smart-M3 piglet-based SIB, its optimized descendant RedSIB, OSGi SIB for Java devices, pySIB for Python devices, and CuteSIB for Qt devices. We also analyze the design of proprietary or incomplete SIB implementations: RIBS for embedded devices and ADK SIB built upon the OSGi framework with integration in the Eclipse Integrated Development Environment. The theoretical study is augmented with experimental evaluation of available SIB implementations.