How could this make sense? Facebook and Linkedin already have considerable revenues. Twitter has zero. They also have far more users than Twitter. And so on. Some have even said Twitter is not a business.

Yet Twitter has a kind of transcendent clarity.

It’s not that Twitter now tops the list of fastest growing social networks or that Facebook offered to buy Twitter for $500 million.

The moment I was introduced to Twitter, my eyes got big. I saw something simple, different and open. It was already evolving through user behavior and through the addition of connecting services. It could be a kind of underlying protocol, the hub of an ecosystem, not a stand alone website.

Today, Tim O’Reilly added to that sense with a wonderful post explaining that Twitter does one small thing and does it well, has brilliant social architecture, cooperates well with others, creates ambient intimacy, and provides core services not bound to a particular interface.

Social networks like Facebook and Linkedin (and Friendster and Tribe.net before them) jealously guard their social graph, the connections between users. So I have to “friend” someone (offering and accepting) separately for each network I belong to, and I can’t take advantage of those connections except in software that run on a particular service. Twitter is different.

Twitter cooperates well with others. Rather than loading itself down with features, it lets others extend its reach. There are dozens of powerful third-party interface programs; there are hundreds of add-on sites and tools. Twitter even lets competitors (like FriendFeed or Facebook) slurp its content into their services. But instead of strengthening them, it seems to strengthen Twitter. It’s the new version of embrace and extend: inject and take over.

An example of that difference comes out in looking at how Facebook and Twitter share status updates.

Last month at CM Summit I asked Evan Williams, CEO of Twitter, about status updates going from Twitter to Facebook, but not the other way.

Today, John Battelle (who interviewed Williams on stage during CM Summit) pointed out a new problem I’d also been facing. It isn’t just that status updates only go one-way, there is also an issue about replies (thus conversation):

I admit that I’m still catching up on Facebook after having overdosed on Friendster and Tribe.net all those years ago. So please comment to suggest things I might be missing.

• Despite having many more Twitter followers than Facebook friends, often my tweets get several more Facebook replies than Twitter @ replies. Why?
• At least where the Facebook user also has a Twitter account, it would be nice to see their comment as an @reply on Twitter so that the conversation could continue there. And vice-versa, I’d love it if my @replies mapped to Facebook (perhaps as a post to that user’s wall?).
• Since it doesn’t work like that, how can I best keep up with that second reply stream? Since I’m on Twitter more often than Facebook, that means I tend to miss them until later. Others may have the opposite problem.
• Another service, FriendFeed, proposes a kind of solution, but in fact, makes the problem worse by providing one more island of comments.
• When I want to continue the conversation, what’s the best way to do that? Respond with an Fbook comment to my own status update? @ reply them on Twitter if I know they have an account there? That seems impractical since I often can’t remember everyone’s Twitter handle.
• Ping.fm, a front-end for posting status to many services, differentiates between updates to “micro-blogs” and “statuses”. Perhaps it will grow to include a category for “replies”? Still, that is only a solution for status going out, it doesn’t solve the problem for replies coming in.

Perhaps the real reason I use Twitter so much more than other social networks is exactly the reason that it is creating this kind of problem. Exactly the reason I felt OD’d on more traditional social networks. By being the most open broadly adapted social network, Twitter becomes the hub for every type of social networking.

Users won’t keep all their lives separated into artificial compartments by service for long. Nor will they keep using many different interfaces to lots of similar services. They have little patience for re-entering and re-confirming their friendships, but they will do it to move to a solution that works better for them. Just as they moved off closed email systems to open ones. Until Facebook develops the kind of clarity that Twitter has, it should fear the fate of Friendster and Tribe.net.

In the end, we’ll flock to the solutions that best increase our ability to be in touch with more people as well as to have deeper connections.Those won’t be the closed solutions.

(Incidentally, I started writing in response to the tweet from John Battelle. In the middle of it, another tweet alerted me to Tim O’Reilly’s post and sent me off in another direction. It’s on Twitter that I keep up with everyone.)

I’d thought the “walled garden” approach to data access on mobile phones was slowly slipping away as more phones support browsing the open Internet, including downloading media that can be used as ringtones or wallpaper.

(Just two years ago a carrier asked us to shut down a program giving away a free promotional wallpapers. They considered it “revenue leakage” since we weren’t selling it and giving them a cut. Now they charge the brand to deliver promotion content free to the user.)

The iPhone arguably replaced one walled garden with three:

1. Works only with AT&T
2. Preventing installation of applications until a future release
3. Requiring that ringtones be purchased from iTunes

Being AT&T-only did provide the benefits of tight voicemail integration, simplified pricing plans and painless activation. Apple may not have been able to get cooperation for that improved overall experience without the exclusive. Maybe that’s a feature rather than a bug.

M-Metrics reports only 2.8% of US mobile subscribers accessed a downloaded application in February 2008. Arguably, Apple is just as concerned with user experience as with any revenue possibilities here. While there are great mobile apps available for most handsets which should be reaching a broader audience, everything is difficult about the old way of finding, downloading and paying for applications.

Will RIM have the vision to apply pressure for similar innovations in its deals with Verizon and Vodaphone, or is the exclusive just another way to keep customers locked in? Please add your thoughts in the comments…