Twitter announced it was buying TweetDeck. TweetDeck is popular, sophisticated client software that makes it far easier to see tweetstreams and searches on your PC, as well as on other devices like the iPad. While the price was not announced, people like TechCrunch are quoting insiders who say the price was at least $40 million.

Ad Age suggests the deal was done to allow Twitter to "Keep control of its own users." This is true: Twitter has already built or acquired popular client software for iPhone, Android, and Blackberry, and other platforms. A rising Twitter developer, UberMedia, was threatening to buy Tweetdeck. Twitter has an open set of APIs, which has allowed a vibrant community of third-party applications to spring up, but also means that the Twitter experience (including how ads are displayed) is not the same for everyone. Now, I expect Twitter to start to offer a common experience on all these devices, combining the best features of the clients it has acquired.

But what does this mean for marketers? Our research shows that about 10% of the influence people have on each other around products and services within social networks takes place in Twitter -- where is this important platform going?

While my former colleague Augie Ray has suggested Twitter will keep a level playing field, my experience tells me otherwise. Twitter will develop new features in its API, especially for delivering appropriate advertising experiences. Those features will deploy first and best in the client software it owns. Marketers dealing with Twitter will get promises about where the experience is going, and Twitter will execute on those promises within its client software. The rest of the Twitter ecosystem has been very useful to Twitter to help it get to this point, but now they will have to play catch-up.

Twitter, which has been a very open system, will increasingly become one where the important interactions are controlled by the company. Just like Facebook. Marketers will have to live within these rules.

This is yet another step in a trend we call the Splinternet. The open, standards-based Web experience that we've embraced for the last 15 years is becoming a set of platforms that people love, but that are controlled by companies (like Apple, Facebook, and now Twitter). While these platforms are exciting, do not be naive: companies control them and will set the rules on how marketers can use them to connect. They'll change those rules as they see fit, which will make your life as a marketer far more challenging. This is the Splinternet era; you'd better get used to it.