A few weeks ago, Twitter suspended two of Ubermedia’s clients from accessing the Twitter API. I was busy at the time and didn’t pay much attention but Twitter’s recent announcement discouraging the development of new Twitter clients and a tweet from entrepreneur/VC Max Niederhofer (“What if the inventor of SMTP had told people to stop building email clients? Will Twitter go the way of Usenet?“) got me thinking about whole affair again.

There’s an interesting dynamic happening here. In principle, there’s no barrier to building an open version of Twitter (or Facebook, for that matter). In fact, SMTP and Usenet are good examples of open, decentralised platforms for e-mail and discussion boards, respectively. There’s no reason you couldn’t have multiple micro-blogging sites, publishing RSS-style feeds that are aggregated on the client side.  But Twitter don’t want that because, in that scenario, the network effects that currently drive everyone to Twitter would be neutralised. A lot of the eyeballs that Twitter wants to display adverts to would disappear, and Twitter would go the way of Compuserve. In fact, there are indications that Twitter is moving away from open standards like RSS.

So, Twitter needs to own its users’ eyeballs in order to generate revenue from them and justify its multi-billion dollar valuation. But what happens if users are accessing Twitter through a third-party app (like Ubermedia’s apps) that connects via Twitter’s API? Ownership of those users’ eyeballs is a little murkier. Arguably, Ubermedia has more control over them than Twitter. If Ubermedia were to add support for other micro-blogging platforms to their clients, Twitter could very rapidly lose it’s dominant position (and the attendant market valuation).

Twitter’s response was to stomp on Ubermedia by suspending its clients. They’d probably like to withdraw support for third-party clients altogether but there’d be a massive outcry and, potentially, the risk of legal action or some kind of FTC investigation, so they’ve settled for making it clear that new Twitter clients are unwelcome. More interestingly, they’ve also made changes to the T&Cs that are clearly designed to prevent developers from siphoning Twitter content into their own micro-blogging service, including a stipulation that third-party clients “must use the Twitter API as the sole source for features that are substantially similar to functionality offered by Twitter” and “may not use Twitter Content or other data collected from end users of your Client to create or maintain a separate status update or social network database or service.”

Exactly what this means for apps like TweetDeck, which includes support for Facebook, MySpace and LinkedIn status updates, remains to be seen. Coincidentally, Ubermedia is rumoured to have agreed to acquire TweetDeck (as if the plot weren’t thick enough already).

It’ll be interesting to see what happens next.