At this point, the most reasonable explanation for Twitter not using Facebook Connect is incompetence. The only real question is whether it’s engineering incompetence or managerial incompetence.

There are reports all over the place about Twitter having too many inactive accounts. I submit that part of the problem is that it’s too damn hard to find real-world friends on the service. As much as Twitter’s biggest fans think it’s about following strangers and celebrities, most people join social networks primarily to interact with people they already know. Twitter has horrible friend-finding tools — they can’t even get most of their users to list real names or location in their profiles. People join Twitter, can’t find anyone they know, and leave.

Twitter had a huge first-mover advantage over Facebook in the arena of multi-platform status updates. Some of its biggest proponents were people who wanted mobile services Facebook and other services weren’t providing. Twitter could have been using Facebook Connect (and/or its buggy Facebook application) to virally promote itself to Facebook users and help users replicate their real-world networks on Twitter. Instead, they’ve been fixating on marginal issues like verifying celebrities and link-tracking.

Now, Facebook is catching up in the mobile arena (with SMS services and an expanded APIT), and you’re seeing an signifcant number of Facebook users describing Twitter as redundant for them. That’s bad news for Twitter.

Twitter is really close to losing whatever advantages it still has. They need to improve friend-finding (Facebook Connect would help, obviously), figure out what still differentiates them from Facebook, and promote that, or they’re going to plateau and crash.

I’d move fast, if I were Twitter. Right now, their biggest feature advantage over Facebook is the ease of @replies, and Facebook’s introduction of usernames will make it very easy for Facebook to copy that feature, too.

Unfortunately, if there’s one thing about Twitter that I’m sure of, it’s that they’re not good at moving fast. I like and use Twitter, but I’m having trouble believing it will still be around in 2 years, just becase I see no sign of Twitter’s management having a clue.

If FB had been forced on me and attached to my Twitter account I would have never joined Twitter.

Don’t alienate people too much, too soon. Twitter must remain “pure” for a while. Otherwise their cousins or twins will replace them fast.

Don’t be Evil too soon John…

Based on Compete’s data I had projected that Twitter would surpass Digg by the end of the summer but it looks like that may have already occurred.

It’s interesting that you suggest that the retention of users may be a problem. I’ve found that according to Compete’s unique visitors for April, the growth rate was diminished from ~100% to ~39%. When Compete’s stats for May are released we should be able to answer the retention question. If it’s down for a second month in a row Twitter could indeed be in need of some serious help.