Update: Facebook has announced that the new “life saving’ tool is “organ donor” status for Timeline. Read about the new feature here.

Facebook CEO Mark Zuckerberg will be announcing details of a new tool “which has the power to save lives” in an exclusive interview with ABC News’ Robin Roberts to be broadcast Tuesday morning. 

A tool that saves lives — what on earth could that mean? A Facebook-branded defibrillator? We doubt it, but then Facebook has had a few surprises up its sleeve lately, so who knows what to expect.

News of Zuckerberg’s appearance on Tuesday’s Good Morning America came via a press release from ABC News, which added that Facebook COO Sheryl Sandberg will also be interviewed — on World News with Diane Sawyer — discussing “the personal stories that led to this new initiative and its goals.”

Excerpts from the interviews will also feature on Tuesday’s Nightline show, as well as on ABC News and Yahoo’s Newsmakers series. ABCNews.com, ABC News Radio and ABC NewsOne will also broadcast portions of the interviews.

Speaking to Computer World, ZK Research analyst Zeus Kerravala speculated as to what the social networking giant might have in store for its millions of users.

“Facebook has location info, so it knows where you are,” he said. “It also knows who you are and who is in your network, including family. With that kind of information, they could build an applet that allows you to broadcast emergency messages through Facebook.”

Along similar lines, the new initiative could be related to Facebook’s partnership with the National Suicide Prevention Lifeline (NSPL). The link-up, which began late last year in the US and Canada, encourages Facebook users who see suicidal comments posted on the site by friends to report them using links on the site. The NSPL then responds by sending an email to the poster suggesting they call the organisation’s helpline.

The news of the life-saving tool comes as Facebook gears up to go public in an IPO that could see the company valued at $100 billion.