Facebook to unveil 'new product' at fourth press event this year

On 20 June, Facebook will once again take the stage to announce "a new product" at its headquarters in Menlo Park, California.

Sent via snail mail, the invites are rolling out slowly; they have reached ABC News and Mashable so far, both of which published a picture of the postcard-like message (above).

"A small team has been working on a big idea," it says. "Join us for coffee and learn about a new product." The otherwise clean white paper has a singular brown coffee-mug "stain" on one corner.

This marks Facebook's fourth press event in six months; so far this year, the social network has revealed Graph Search in January, a revamped News Feed in March, and most recently, the Facebook Home Android experience.

Mashable pointed to November's testing of price points for a Facebook postcard service, wondering if the physical invitations aren't a clue to the big announcement. Meanwhile, ABC News tipped the company's recent remarks about "making additional announcements over the coming weeks about its public conversation features."

Last week, product Manager Greg Lindley introduced Facebook's clickable hashtags service, commenting in a blog post that "To date, there has not been a simple way to see the larger view of what's happening or what people are talking about."

But hashtags are just the first step "to help people more easily discover what others are saying about a specific topic and participate in public conversations," he said. Facebook is prepared to roll out more features in the coming weeks and months, including trending hashtags, deeper insights, and perhaps whatever this mysterious coffee-stained announcement is.

There have also been rumours that Facebook is developing its own RSS reader ahead of Google Reader's 1 July shutdown.

Let the gossip begin, and stay tuned on 20 June for more details straight from Facebook.