Monitor Duty covered this awhile ago and had the link to the video, the then-new Wikipedia entry, and a link to something about gamer slang.
A lot has happened since then, and I have devoted a lot of time to something that's irrelevent to normal humans, so I hope someone is grateful for the peek into a subculture of gaming that even I do not belong among.
It turns out that in the end an entry devoted to an internet meme is not good enough for the Wikipedia tyranny-of-the-elitist-mob establishment and the entry was deleted with the URL used to redirect browsers to the World of Warcraft regular entry, as one would notice by clicking the link. Information regarding Leeroy Jenkins was inserted into that entry, insuring some relevence. The compromise seems just; the volume of information on Jenkins is less, but what's found has a telling effect. If Wikipedia is credible (and from my experience and knowledge, it usually and generally isn't) then the whole failed raid was staged in order to promote the player's guild. The event that made Leeroy Jenkins such a hot topic among darkened-room-dwelling virgins and other net-addicts was phony and an act of vanity. This makes sense, of course, since the battle was video-taped. How much mass-role-playing action is video-taped, and how many players do it?
Another interesting thing is that even though the Monitor Duty post and link were created on May 25, 2005, the only existing Wiki entry on the topic is dated and time-stamped for 08:53, 30 May 2005. The final revision made to the article before it was deleted and the data folded into the World of Warcraft topic is different than the one I remember reading from the link I originally used on Monitor Duty back on May 25. The words are different and there's less information. The entry as it last was reads
"Leeroy Jenkins" is a person from the PC game "World of Warcraft." His notable action was being AFK while a raid was being planned, and then returning and saying "Alright chums I'm back. Let's do this! LEEROY JENKINS!" He then runs in, and is followed by his entire party. The planned raid failed horribly because of his actions, and everyone died. After quite a bit of swearing at Leeroy, there is brief silence; Followed by Leeroy saying "At least I got chicken." No one understands the last line, though it's possible he is actually saying "At least I'm not chicken." Leeroy is a very intelligent, masculine fellow, who only seeks the best for him and his "guild". "One day," Leeroy exclaims, "I want to be the very best, like no one ever was."It's fascinating that this is the only version/revision in the Wikipedia records, especially since there should be more. If nothing else it's illogical that the item Monitor Duty references was created five days after the words that referenced it. Wikipedia doesn't acknowledge any other copy. The original, I believe, also had links.
It's likely that Leeroy Jenkins and company did stage the whole thing but it did create a slight ripple amongst his intended audience and the video (this link is cribbed from the Wikipedia World of Warcraft entry) is good for a few laughs. The genuinity of the Leeroy Jenkins incident is irrelevent and unimportant in the long run but it is is a good thing to affirm the importance of truth in general. As it is the Wikipedia community readers, and others looking for knowledge on the incident regardless of source credibility, truth, and bias can find the stuff here. The Leeroy Jenkins URL redirects the browser to the general entry, which is inconvenient for the searcher; a more apropriate redirect would take the reader directly to the Community subtopic where it would be easier to find the information, have less irrelevent data in the way, and serve the link (as well as users) better.
Wikipedia is not actually a place for good information and service. Using it is always at one's own risk and when listening to the ballad of Leeroy Jenkins one should take it with a grain of salt.