Blogger Sam Johnston did some digging around the U.S. Patent and Trademark Office and discovered documents indicating that Twitter's attempt to trademark tweet was preliminarily denied, as three other companies with tweet in their names had already submitted similar applications.

The three companies, according to CNET, were: TweetMarks, which offers bookmarks for Twitter users; CoTweet, which helps businesses run marketing campaigns via Twitter; and TweetPhoto, which enables photo sharing via the social-media service.

On July 1, the same day the Patent Office sent its notification to Twitter that its application regarding tweet had been preliminarily rejected, Twitter co-founder Biz Stone used the company's blog to attempt to clear up the confusion over the use of the words Twitter and tweet by third-party developers.

Stone's July 1 post:

The ecosystem growing around Twitter is something we very much believe in nourishing and supporting. There are lots of really awesome services and applications out there like TweetDeck, TweetMeme, Tweetie, BackTweets, Tweetboard and others that we absolutely love, as do many users. However, as the ecosystem grows, there is also the possibility that confusing and potentially damaging projects could emerge.

We have applied to trademark Tweet because it is clearly attached to Twitter from a brand perspective, but we have no intention of "going after" the wonderful applications and services that use the word in their name when associated with Twitter. In fact, we encourage the use of the word Tweet. However, if we come across a confusing or damaging project, the recourse to act responsibly to protect both users and our brand is important.

Regarding the use of the word Twitter in projects, we are a bit more wary, although there are some exceptions here, as well. After all, Twitter is the name of our service and our company, so the potential for confusion is much higher. When folks ask us about naming their application with "Twitter," we generally respond by suggesting more original branding for their project. This avoids potential confusion down the line.

Thanks to Robin Wauters at TechCrunch for raising the issue because it highlights a need. As we build our platform team, we will be adding more documentation, guidelines and best practices to help developers get the most out of our growing set of open APIs. We'll work together to ensure success for Twitter, developers and everyone who uses these services while avoiding confusion and maintaining quality.