The usual game dev crowd is buzzing about the slide presentation Raph Koster has up, from a talk he gave at the Korea Games Conference. It's thought-provoking and really quite beautiful in its own right. I highly recommend taking a look.
In it, Raph seems to be indicating that user-created content, or a cousin of it, is where we're all headed. There's a lot of success from that quarter already, with mod development happening in games from The Sims to Quake. The Movies seems to be banking on this trend, too. Not to mention the likes of Second Life, which exists primarily as a vessel for users to create content.
To bring it back to ARGs: user-created content is a tough line for us to walk. It seems like we'd be a shoo-in for it, from fanfic and fanart to entire chunks of in-game world fleshed out by a loving audience. There are some nasty ramifications in ARGdom, though, both from a legal perspective and from a social one.
In the case of games such as Metacortechs, which I believe took place in the world of The Matrix without any sort of prior authorization, the IP owner apparently gave a bit of a wink and a look away through the whole thing. That's not to say that every company could react in the same fashion. Even in the case of a company such as Mind Candy, where the IP is owned by the creator of the ARG, I believe it's not legally clear whether allowing players to independently create and distribute content presenting itself as from Perplex City would put the company in jeopardy of losing its rights to its intellectual property entirely. We'd be kind of obligated to defend our continuing existence of a company.
On the other hand, my own experiences with player-created content in the ARG world have been resoundingly negative, anyhow. Any such effort historically puts the playerbase into a frenzy of worry about whether something is canon and in-game or not (consider, in the A.I. Game, the angst provoked by the BWUNN site). And from the puppetmaster point of view, allowing an externally controlled element to become game canon is very dangerous to your plot and planning. If John Q. Protagonist points to fanfic.weblog.com one week as containing some hot news, he can't go back to pretending he's never heard of it the next week when fanfic.weblog.com starts talking about larger meta issues that destroy the immersiveness of the game, or when it starts introducing its own plot elements, or proof that B is the villain when you'd been setting it up to do A, etc., etc.
A sticky wicket, one might say.
So I'm not sure yet how Raph's prognostications regarding the destiny of gaming as a whole pertains to ARGs in particular. Maybe I've misunderstood his whole point, or maybe ARGs have a somewhat different destiny, or maybe I (or Raph :) just plain have it wrong. If you've got any ideas, please feel free to drop a comment.