Font Awesome is fully open source and is GPL friendly. You can use it for commercial projects, open source projects, or really just about whatever you want.

**Attribution is no longer required as of Font Awesome 3.0 but is much appreciated: "Font Awesome by Dave Gandy - http://fontawesome.io".

Font License
    Applies to all desktop and webfont files in the following directory: font-awesome/fonts/.
    License: SIL OFL 1.1
    URL: http://scripts.sil.org/OFL

Code License
    Applies to all CSS and LESS files in the following directories: font-awesome/css/, font-awesome/less/, and font-awesome/scss/.
    License: MIT License
    URL: http://opensource.org/licenses/mit-license.html

Documentation License
    Applies to all Font Awesome project files that are not a part of the Font or Code licenses.
    License: CC BY 3.0
    URL: http://creativecommons.org/licenses/by/3.0/

Brand Icons
    All brand icons are trademarks of their respective owners.
    The use of these trademarks does not indicate endorsement of the trademark holder by Font Awesome, nor vice versa.
    Brand icons should only be used to represent the company or product to which they refer.