Vexillum is a Cydia tweak that makes it possible to change the color of your notification banner and the color of the font. There are other tweaks similar to this one, such as ColorBanner, but this one is free and allows you to chose any color you would like, using an RGB color module. All configurations for this tweak are done in the settings application, under the Vexillum tab. Check out the video review below.
Vexillum works just as advertised and is very stable and smooth. Again, Vexillum is available now in Cydia, in the ModyMyi repo for free.