The last compilation of ultra wideband (UWB) communications systems is nearly two years old (see Fontana, R.J., Ultra-Wideband, Short-Pulse Electromagnetics, EuroEM 2000). This paper is intended as an update and illustrates recent trends in UWB communications for multi-user networking applications. More specifically, the paper describes three recent system developments: an ad hoc wireless UWB communications network for tactical voice and high-speed data communications; a long range UWB system for over-the-water and non line-of-sight voice, data and video communications; a wireless UWB communications network for support of both tactical and strategic (long haul) communications.