Is organised religion considered to be an evolutionary development?

Most people like to think of organised religion as being "special", inspired by some transcendent spiritual awareness or experience rather than by any evolutionary process. However, many biologists have explored the ways in which social organisation in general and moral imperatives specifically are rooted in our evolutionary history, and there are some intriguing ideas out there.

For speculation about the earliest roots of a formal morality, see my answer at http://www.answerbag.com/a_view.php/32303. However, far beyond this, it has been well-mapped by anthropologists and archaeologists that as societies became larger, social stratification increases, people are able to acquire specialised roles, and societies develop both a "priesthood" and a "nobility" who do not have to work to feed themselves, but are fed by others in return for providing organisation and direction. This can be regarded as part of cultural evolution, rather than biological evolution. There is undoubtedly more information on this available in the field of "Anthropology of Religion", although I'm not sure what recommendations to make. You might try "A Reader in the Anthropology of Religion" edited by Michael Lambek.

For discussions of the possible biological evolutionary origins of formal codes of behavior and ideas of deity, I recommend reading work by Frans De Waal and Daniel Dennett (especially "Breaking the Spell : Religion as a Natural Phenomenon", bearing in mind that Dennett is guaranteed to piss some people off mightily by his treatment of religion) -- http://www.amazon.com/gp/search/ref=nb_ss_b/102-1989013-6002542?url=search-alias%3Dstripbooks&field-keywords=Frans+de+Waal&Go.x=0&Go.y=0&Go=Go , http://www.amazon.com/gp/search/ref=nb_ss_b/102-1989013-6002542?url=search-alias%3Dstripbooks&field-keywords=Daniel+Dennett&Go.x=0&Go.y=0&Go=Go.

For a couple of interesting pieces on the topic available online, I suggest the interview with Frans De Waal in "Science & Spirit", http://www.science-spirit.org/article_detail.php?article_id=184, and a book review of "Wondrous Healing: Shamanism, Human Evolution, and the Origin of Religion" by James McClenon, in the Journal of Religion & Society at http://moses.creighton.edu/JRS/2002/2002-r10.html. This will give you an idea of the kind of material out there, and some of the ideas that people have on it.