"Facebook's Mark Zuckerberg says the company's aim is to be the home screen of any Android mobile."

The long rumored Facebook phone turned out not to be a phone at all.It is a software called Facebook Home that makes it easier for people to spend more time on Facebook. 
A phone from HTC that comes pre-loaded with Facebook Home will  be available April 12, with AT&T as the carrier.

HTC First is the first "Facebook Home " optimized phone in the world.It will be available in four colors (black, white, red and pale blue) and it costs $99.99.
HTC First facebook-phone in black color showing back,front and side view

The idea behind the "Facebook Home " software is to bring Facebook content right to the home screen, rather than requiring users to check apps.
The main aim of introducing "Facebook Home " is to increase the number of people using Facebook from phones and tablet computers. Of its 1.06 billion monthly users, 680 million log in to Facebook using a mobile gadget.
The deeper mobile integration will likely help Facebook to attract more mobile advertisers.