A couple of commenters (possibly not so politely) pointed out that this looked an awful lot like a conflict of interest, and were promptly banned.
Wow… just wow.
John Scalzi weighed in on the comment thread there and noted that it is possible for media outlets to review things that are paying their salaries. This is entirely correct. What io9 is doing, however, is the exact opposite of the way you're supposed to do it.
But let's give them the benefit of the doubt, and assume that their opinions about District 9 are entirely on the up and up and not influenced by the wads of cash their advertising folks are getting from the film's promotion team. You do not ban people from commenting because they have noticed the possible conflict of interest.
I normally avoid any hint of my real life on this blog, but I'm going to now. I'm a reporter at a smallish suburban newspaper. This means I have many jobs, including writing a weekly column, covering local politics and crime, and sometimes writing the editorials (we sign our editorials, as they do in Quebec, by the way). When you piss people off (and you will piss people off) and they send you an angry letter, YOU PRINT IT!
Oh, I'm sorry, did I just yell? Well, maybe I'm a little ticked that io9 doesn't understand the basic rule of running a media business that says disagreement is actually good. Sure, you can delete posts and ban users, and no one will be left after a while to criticize. They will tell you how awesome you are and stroke your ego. And slowly they will slip away, and you will be an irrelevant joke.
I actually like io9. I know it exists mainly to be all ZOMG NEW IRON MAN TRAILER!!!!1!, but I like that they actually write about books on a regular basis. They even interviewed Samuel Delany a while back. It's refreshing to see a site that gets 99 per cent of its hits from people interested in the next cheap pseudo-SF blockbuster, and devotes 10 to 20 per cent of its time to talking about stories printed on dead trees. Considering how often they update, you actually get more book reviews, recommendations and author interviews out of io9 than out of almost any other SF-related site on the web.
If io9 would like to explain how their actions are anything less than petty protection of their sponsorship, I'd love to hear it.