Facebook's Tuesday Event: What Will Mark Zuckerberg Say?

Facebook is holding an event on Tuesday. What could it be announcing?

Jan. 14, 2013 — -- While many of the major technology companies (Samsung, Sony, etc.) descended on Vegas last week for CES 2013 to announce new hardware and software products, Facebook decided to hold off on its big news until this week.

Tuesday, Jan. 15, Facebook will hold a private press conference at its headquarters in Menlo Park, Calif. "Come and see what we're building," reads an invitation sent by Facebook to ABC News last week.

That small line has set off some big speculation about what the social network might show off tomorrow.

TechCrunch's MG Siegler reported over the weekend that the event will be mobile focused and could even bring a "Facebook phone" of sorts.

MORE: A Facebook Phone? Company Testing Voice Apps Now

"And so, with that in mind, multiple sources have told us that they expect some sort of Facebook Phone to be on display on Tuesday," Siegler wrote. "Now for the caveats (and they're important). It's not entirely clear if this will be an actual piece of Facebook branded hardware or if they will simply use hardware from a phone maker to show off some sort of new Facebook OS for mobile. That is to say, it could very well be that the 'Facebook Phone' is more about a Facebook OS running on a phone (or a few phones)."

ABC News made a similar argument about Facebook's move into the mobile phone world last week, pointing out that Facebook has announced multiple apps (Poke, Camera, iPhone and Android refreshed apps) in the last few months and even added voice calls to its Messenger app. Mark Zuckerberg has denied rumors of a Facebook-built phone in the past, saying he would prefer the company to build on current platforms.

"There are a lot of things you can build in other operating systems as well that aren't really taking, that aren't really like building out a whole phone, which wouldn't make much sense for us to do," Zuckerberg said during an earnings call in July.

RELATED: Facebook May Be Changing Your Timeline: Redesign Tests in Progress

But others are thinking it might just have to do more with greater mobile services. "I think what Facebook is about to do is a new kind of discovery engine. Because there is so much data in Facebook," Robert Scoble, a social media and app expert, said. Scoble concluded that Facebook's new service would have a major mobile tie-in and that Facebook is thinking about how it can better surface and present the data it has collected from its 1 billion users.

In September, Zuckerberg also hinted that Facebook could compete against Google and Microsoft's search engines. "When you think about it from that perspective, Facebook is pretty uniquely positioned to answer the questions people have. What sushi restaurants have my friends gone to in New York in the last six months and Liked?" he said at TechCrunch Disrupt. "These are questions that you could potentially do at Facebook if we built out this system that you couldn't do anywhere else. And at some point we'll do it. We have a team working on search."

Another possibility? Facebook has also been testing some new Timeline designs, including doing more with content partners, including Spotify and Pandora.

But until Tuesday at 10:00 a.m. PST/1:00 p.m. EST, Facebook fans will be left searching for what Facebook's big news is. ABC News will have the latest on tomorrow's event.