The combination of real-time message delivery and presence awareness has to lead the rapid rise in popularity of Instant Messaging (IM) in recent years. The extension of IM to mobile ad-hoc networks certainly offers considerable potential. However, the dynamic topology and decentralized nature of these networks requires several major issues to be addressed. Specifically, difficulties exist in providing an effective reliable service in the absence of a continuously available server. We present here the Dawn IM system, which takes a decentralized approach to bringing the functionality inherent in fixed-network IM systems to an ad-hoc environment. In addition we discuss a test-bed implementation that supports collaboration between users equipped with handheld devices.