It's a custom font set, using css @font-face like Typekit, and Google Fonts are for example. So so just like characters in a font, the icons can use the same t

It's a custom font set, using css @font-face like Typekit, and Google Fonts are for example. So so just like characters in a font, the icons can use the same text effects like any other text, like size, coloring, gradients, text-shadows and etc, which can save you a lot of time and maybe bandwidth too. We used Pictos fontset on our RailsRumble app (http://splendidbacon.com http://splendidbacon.com) a while back and it was much better and faster experience for me, than building the different icon colors & sizes in Photoshop like usually.