A quick note: a couple of days ago, I acquired a copy of Ancient Religions of the Austronesian World by Julian Baldick, a scholar of religion, formerly of King's College, who unfortunately died last year. This was his last book and, as the title says, it is an attempt to identify commonalities and differences in the religious beliefs of speakers of Austronesian languages. It's up-to-date, has excellent recommendations (e.g., from James Fox), and is quite good reading. I saw a copy in Blackwell's (although I bought mine online), and as it is rare for books like this to be published, and as it cites most of the major ethnographies of eastern Indonesia and the Pacific - super-underrepresented areas - I'm glad it exists.
I'm about halfway through, and it has been reasonably good so far. Needless to say, it covers more ground than merely what we would classify as religion. There are a few basic mistakes, actually - typos, of course, but also some accuracy issues, as will happen with any work of similar scope. For example, Baldick calls the majority ethnic group of West Timor the 'Atoni', instead of the now-more-common name, Meto. It is notable that despite relying on 'Atoni' evidence for some of the book's conclusions, the bibliography contains none of the work of Andrew McWilliam, even though McWilliam has written extensively on Austronesia, the Meto, and even headhunting, one of the core features of Baldick's vision of proto-Austronesian culture. He also misses out R. E. Downs's article on headhunting in Indonesia, which is still key to discussions of it.
I also have a bit of a problem with the presentation. For a start, there are no maps or diagrams that would help clarify the relationship between the various branches of Austronesian or their geographic distribution. Baldick took the Indo-Europeanist Georges Dumezil as an inspiration and arranged his book the way Dumezil organised his, with separate sections on Western, Central, and Eastern Malayo-Polynesian speakers (never mind that these are artificial divisions) and a conclusion that attempted to draw out the similarities. I much prefer the approach of M. L. West, a classicist whose work on Indo-European religion, poetry, and myth is perhaps the most interesting you'll find. West divides his book on the basis of topic, with separate sections on poetic metre, storm gods, and warfare (&c.), which is a much more effective comparative device, to my mind. But I suppose your mileage may vary.
I'll be reviewing the book as soon as I've finished reading it. Until then, though, I recommend it. If you're at all interested in ethnology, prehistory, or the limits of what can survive in human communities from such great time depths, then it is certainly worthwhile reading.