Twitter co-founder Biz Stone on Thursday said that the popular online messaging site had updated its Terms of Service to clarify what users can expect from the service, though the announcement appears to be more about reassuring users than delineating substantive rights.

The move suggests a desire not to repeat the controversy that Facebook found itself in when, in February, the social network altered its Terms of Service and users read the language as a claim of ownership over all user-submitted content.

"The revisions [of Twitter's Terms of Service] more appropriately reflect the nature of Twitter and convey key issues such as ownership," said Stone in a blog post. "For example, your tweets belong to you, not to Twitter."

This does not appear to be much of a change, however. Twitter's Terms of Service from October 2007 state, "We claim no intellectual property rights over the material you provide to the Twitter service. Your profile and materials uploaded remain yours."

Such assurances may mollify twittering authors of note but they're not particularly meaningful.

"The vast majority of tweets are likely to be too short and lacking in creativity to qualify for copyright," said Fred von Lohmann, senior staff attorney for the Electronic Frontier Foundation, in an e-mail. "So they are not 'owned' by anyone, much like your idle chatter while walking down the street isn't 'owned' by anyone."

Lohmann however grants that there are exceptions, such as a carefully-crafted haiku that was tweeted.

As far as the U.S. Copyright Office is concerned, short phrases don't qualify for copyright protection. The Copyright Office's Compendium of Copyright Office Practices states, "Names, titles, slogans, and other short phrases or expressions are not copyrightable, even if such expressions are novel, distinctive, or lend themselves to a play on words. Similarly, a mere listing of ingredients or contents is not copyrightable."

Tweets -- the messages of up to 140 characters that users send using Twitter -- appear to exist in a gray area.