A week ago I asked a question about when early Judaism coalesced into a recognizable form, and received some helpful answers. (Link for reference:http://www.reddit.com/r/AskHistorians/comments/2fyir4/when_did_judaism_coalesce/)

Reading about ancient Israel and polytheism, I was curious about a fascinating psalm I came across. It's Psalm 82, and in this work Yahweh 'demotes' a whole bunch of pagan gods for being unjust, failing to defend the poor and helpless, and favoring the cause of the wicked. (Link here: https://www.biblegateway.com/passage/?search=Psalm%2082) An article I read argued that this was probably a very old psalm.

My question: What do we know about Psalm 82 and its composition, its themes, subject matter, and when it was written? Is it a celebration of Yahweh's triumph over the gods of other peoples, or a remnant of early Israel polytheism, or something else?