Below you'll find FaceBook Blue along with 4 other shades of blue used on the Facebook site. The second color is Facebook Blue. The other 4 blues are accent colors. White and Black are also part of the palette.
The basic Facebook logo is a rounded blue square with a white lowercase f. Very simple and easily recognizable.
If you're interested in the font, you can find one similar to the Facebook font on DailyFont.com. It's not quite the same, but it's close.
If you're interested, Facebook has a site dedicated to their branding where you can download logos and screenshots and get information about the right way to use Facebook resources.