This volume edited by Sasha Aikhenvald and R.M.W. Dixon collects most of the papers presented at a 1998 workshop at the Research Centre for Linguistic Typology in Australia.
Most of the papers presented at the workshop engaged in some way with Dixon's theory of "punctuated equilibrium", which had been introducted the year before in his essay The Rise and Fall of Languages. The expert on Australian aboriginal languages had long been struck by how Australian languages show shared features across the continent, but no higher-level genetic grouping can be determined. According to his view of history, languages have undergone thousands of years of relative equilibrium marked by areal convergence, "punctuated" by sudden cases of language change due to migrations, natural disasters, etc. This theory is amply summarized in Aikhenvald and Dixon's introduction to this volume.
Peter Bellwood is an archaeologist with an interest in historical linguistics. His paper "Archaeology and language family origins" suggests that the "punctuation" which lead to the rise of a handful of major language families worldwide several millennia ago was the development of agriculture. Unfortunately, he thinks that IE spread with the first farmers out of Anatolia, and I (and most linguists) don't believe that this theory holds water.
Calvert Watkins contributes a paper on Anatolian as a linguistic area that offers evidence against Dixon's theory. He describes convergence in phonology and syntax between IE and non-IE languages of Anatolia in the second millennium BC, and between Anatolian languages and Greek in the first millennium BC. He takes issue with Dixon's hypothesis by noting that IE Anatolian and non-IE Anatolian converged rapidly over a period of less than five centuries, that is, during the "punctuation" of IE languages entering the area, and not during a long period of "equilibrium".
Other papers deal with language families somewhat outside my ken. Of course, even if Dixon is wrong about this particular theory of his, he has much insight into Australian aboriginal languages. He contributes a paper on the Australian linguistic area and his colleague Alan Dench on Pilbara specifically. Geoffrey Haig examines diffusion in present-day East Anatolia, not just pan-Anatolian features but Turkish-Laz and Turkish-Iranian contacts in particular. Sasha Aikhenvald, who is especially interested in languages of Amazonia, writes on problems of subgrouping in North Arawak. Malcolm Ross contributes a paper on contact-induced change in Oceanic languages of northwest Melanesia.
Heine & Kuteva discuss convergence and divergence in Africa, while Gerrit J. Dimmendaal gives his own perspectives on areal convergence versus genetic inheritance.
The Sino-Tibetan family is investigated in two papers. Randy J. LaPolla looks at the role of migration and language contact in Sino-Tibetan, while Hilary Chapell writes on language contact and areal diffusion within Sinitic specifically.
A couple of papers are concerned with Southeast Asia. James A. Matisoff writes on prosodic diffusibility in the area, while N. J. Enfield points to parallel polyfunctionality of the verb 'acquire'.