Update | Click here for an update to this post. The more I dig, the more I think something weird is going on here.

A week ago I wrote a piece on why the hashtag #Wikileaks wasn’t appearing on Twitter’s trending topics lists, concluding that Wikileaks’ failure to trend was an artifact of an actually-quite-reasonable-really algorithm, and shouldn’t be taken as evidence of anything nefarious.

Okay. That was then. But in the intervening week, Wikileaks has seen a truly staggering amount of traffic on the site, and still hasn’t trended once.

How staggering? This staggering:

Back in the summer, the title of the movie Inception peaked at 0.4% of Twitter traffic, soon stabilizing at about half that. It trended for a month and a half. Wikileaks has broken 2.0% of total traffic twice in the last week, and hasn’t yet dipped below Inception’s all-time high.

Want more? Here’s more. Wikileaks had more traffic than “world aids,” the week’s longest-trending phrase, for all but three hours of the week. It out-trafficked Bieber and Obama by wide margins. It was more popular than Jesus by an order of magnitude. At its peak, it appeared more frequently on Twitter than the word “or.”

And here’s my favorite … on five separate occasions in the last week, including eight hours on Friday and two hours on Saturday, “wikileaks” was getting more traffic than “twitter.” On Twitter.

Okay. So does all this prove that Twitter is blocking Wikileaks from trending?

No.

Not exactly. Not quite.

For one thing, as I posted last week, Twitter’s trending topics don’t — and shouldn’t — just reflect raw traffic. As the company explained back in May, when they overhauled their algorithm, it’s designed to catch “topics that are immediately popular, rather than topics that have been popular for a while or on a daily basis.” Since Wikileaks has trended before, it’s now got a higher bar for trending again. (This explains why the alternate Wikileaks hashtag #cablegate trended for a total of 22 hours last week, despite having consistently lower traffic than Wikileaks itself. Because it was a new tag, it got the algorithm’s attention.)

For another thing, not all tweets are equal in Twitter’s eyes. As the site’s trending topics FAQ notes, they take a dim view of folks who try to game the TT list by flooding the service. “The most important thing,” they say, “is to make sure your Tweets are genuine thoughts or impressions and not attempts to insert yourself into a trend.”

This is likely a partial explanation for the incredible trending run that Inception had this summer. Inception wasn’t just a popular movie, it was a controversial and confusing one — one that got people discussing, not just tweeting. I haven’t gone back and checked, but I have a very strong suspicion that an unusually high proportion of Inception’s tweets during its reign were brand-new content — much higher than that of recent Wikileaks tweets.

It’s also possible, given Twitter’s warnings on its FAQ page against “repeatedly tweeting the same topic/hashtag without adding value to the conversation in an attempt to get the topic trending/trending higher,” that efforts to get Wikileaks to trend — or even discussions of why Wikileaks wasn’t trending — could have pushed the topic down on the TT lists. (Which means, for instance, that the folks who are tweeting about Wikileaks’ failure to trend under the #thingsimiss hashtag are likely hurting Wikileaks’ chances of trending.)

Finally, I have to at least acknowledge Twitter’s denial that they muck with the trending topics list for political purposes. A few days ago, a similar controversy arose in relation to the failure of #demo2010, the hashtag of Britain’s student protesters, to trend in that country. Asked for comment, a Twitter spokesperson told The Guardian that there was “absolutely no truth” to the charges. “We have not,” he said, “and will not, do anything to stand in the way of people using Twitter for the open exchange of information.”

So does that settle it? A week ago I thought so. But I have to admit that the sheer scale of the Wikileaks traffic since then gives me pause.

I still think the vast majority of TT conspiracy theories are bunk. Twitter wasn’t censoring #demo2010, I’m certain. There’s no evidence that it censored #cablegate. It’s not censoring #imwikileaks, as some have charged — that hashtag just hasn’t taken off in any serious way.

I’m also unconvinced that Wikileaks trending on Twitter would be all that big of a deal. Huge numbers of people are participating in Wikileaks discussions on the service — if the goal was to stifle conversation, it failed. Trending on Twitter is an easy measure of a subject’s influence, and in a weird way a sort of badge of honor, but it’s not obvious to me that it has a huge effect on a story like this.

To be honest, this is another reason that I tend to doubt that Wikileaks was censored — to do so would pose a huge risk to Twitter’s credibility with its audience, and for very little reward.

But if Wikileaks’ failure to trend is an artifact of Twitter’s algorithm — and that’s still my default guess — it’s a really screwed up algorithm. Because Wikileaks has been the biggest story by far on Twitter this week, by any measure. It’s a huge story. It’s an important story. It’s a breaking story. It’s an evolving story.

It’s the very definition of a trending topic.

So why isn’t it trending?

Update | As I noted at the top of this post, I’ve done a visual comparison and anaylsis of traffic for “Wikileaks” and “Sundays.” You can find that post here, and I expect you’ll find it as startling as I do.