CNN reported this week that Twitter subscriber growth had peaked and that visits to the site were relatively flat. This information doesn’t seem to match the reports from Twitter itself that the number of tweets per day keep growing and that the engagement of users has increased.
What else could be going on here? A key component of Twitter’s growth is in the mobile and client space — people accessing the service through smartphones and using clients such as Tweetdeck and Seesmic to access the Twitter API — and these users may not show up directly.
Mobile internet growth has not yet peaked (Apple has sold 42m iPhones on a 1 billion+ base of all mobile phone users, e.g) and only about a quarter of internet users use mobile internet services. Clearly, major growth is still to come for real-time services and the Internet — it just might not happen on the web browser but through other clients. Twitterific or Tweetie might appeal to users of the new Apple Tablet — and there are surely other devices to come.
So what’s CNN’s motivation for calling a peak on Twitter? First, Twitter’s a threat to the core CNN business, offering real-time news faster and (potentially) more accurate than the CNN reporting itself. MSNBC recently purchased the @breakingnews twitter handle and it is now an arms race to deliver a mix of curated crowdsourcing, breaking news, and expert opinion to be a news organization today. It would be great if CNN would respond to this challenge by offering better content in every news channel (mobile, web, tv, etc.) … let’s hope it happens.
Information Maven 
I looked at the CNN article and didn’t smell any obvious bias or shoddy reporting. It acknowledged all of the issues you raised (increased engagement per user, increased access on mobile devices, etc.). Also, if CNN were letting the threat of new media creep into how it reported the story, you might expect the story to suggest some broader trend about new media fizzling out. However, the story contrasted the trend in Twitter user numbers (22 million and holding) with the continuing upswing in Facebook numbers (350 million and rising). To me, that’s an interesting, potentially newsworthy contrast. It doesn’t mean that Twitter has “jumped the shark” (or whatever the appropriate phrase is these days), but it does suggest some possible differences in the two sites’ relative capacity for growth.
Excellent points, Greg, though I disagree with your assessment of user numbers. Various sources this week have suggested that Twitter may have as many as 75 million users (though perhaps only as few as 15 million active users). If this true Twitter is actually growing quite quickly and I would expect it to continue to grow faster percentage-wise on a smaller (50-75m base) than the larger Facebook (350m base). This disparity or inconsistency in statistics was the basis for my post, along with the fact that CNN and Twitter are essentially chasing some of the same audience for real time news. I think there’s a very real possibility for a conflict of interest here.