Blogs privilege the “now.” New stuff always goes on top. But they also create a durable record of “then” — as I have learned in spending the last couple of years digging through the back catalog of blogging. One of the great contributions of blogging software is to organize the past for anyone who writes frequently online. Before blogs, with each new addition to a website we had to think, where does this go, and how will I find it later? Blog tools, as personal content management systems, ended that era.

Twitter is great at “now.” But as far as I can tell, it’s lousy at “then.” It offers no interface to the past. You can’t easily navigate your way backwards in time.

Recently, I wanted to figure out the date of my first tweet. It’s still there in the database. But there’s no simple way to locate it. (Folks on Twitter pointed me to services like mytweet16 that dig up your oldest tweets, or tweetbook.in, which puts your whole Twitter history into a PDF, so there’s a way to do it, but not much of a useful interface.)

Each tweet is timestamped and lives at a unique URL. So it should be possible to build the machinery to organize one’s tweets into a more coherent record. (Dave Winer has written about this and done some work to store his Twitter past.) But — again, as far as I’ve been able to determine — we don’t really have a clear sense, or commitment from Twitter the company, of how long these URLs are going to be around.

The other big weakness of Twitter as a sort of universal microblogging platform is that all its interaction is happening on one company’s server, in that company’s database. That poses some fierce technical problems if the Twitterverse keeps scaling up. (See for instance this comment by Chuck Shotton at Scripting News: “IMO, Twitter is a toy to be experimented with until it breaks and is replaced by a properly implemented solution that will persist, scale, and be as open as the protocols above.”)

If Twitter can engineer its way out of the scaling dilemma, we’re still looking at a platform that is owned by one company. One of Dave Winer’s original message as a proto-blogger in the mid-90s was to warn us about such platform ownership and to celebrate the arrival of the Web as the platform that nobody owns. Today Winer is sounding the same alarms about Twitter, and they are worth weighing. While I find Twitter far more open to the Web than, say, Facebook — which really feels like an AOL-style walled garden — it’s still just one company, with one “namespace,” or set of unique names for people to claim (good Twitter IDs will probably run out even faster than domain names).

To date I think Twitter has done a pretty fine job of serving its platform and its users — though I have qualms, as many do, about the way its Suggested User List mixes up editorial and business roles without taking full responsibility for either. But once the company decides it’s time to “monetize” — whether that happens next month or year or decade, and whether it’s handled sensitively or crudely — we are likely to see old-fashioned conflicts between serving users and serving the quarterly revenue targets re-emerge.

Best case: Twitter hits a home-run by finding an innovation that, like Google’s targeted text ads, brings in revenue without degrading the primary service. (There is a subtle argument — espoused by Rich Skrenta and others — that Google, in monetizing its pages, corrupted the link-ranking on which its whole search engine depends. But for most of us, Google managed to make a fortune without noticeably reducing its usefulness — a neat feat.) Worst case: Twitter fails to figure out a business model and its investors grow impatient, forcing the service to overload us with advertising like a tanking dotcom in 2001.

On his blog at BNET, David Weir recently recorded the following comment from an anonymous Silicon Valley insider: “Twitter is exactly what the Internet was around 1996. It represents nothing less than the New Internet. It is the game-changer.”

I share the general enthusiasm for Twitter as a model for real-time interaction. But I don’t fully buy the “New Internet” notion. By 1996, people like me (and David Weir, and Evan Williams, and Dave Winer, and countless others) had flocked to the Internet because it was wide open. In the World of Ends formulation, “No one owns it. Everyone can use it. Anyone can improve it.” Twitter, exciting as it is, falls far short of that kind of game-changing.

[This post follows on from yesterday's How Twitter Makes Blogs Smarter.]