Quantum is a new tweak released today in Cydia, and with its help you can change the fonts of the notification banners displayed in iOS 5. Apple has set a certain font for titles and messages, but with the help of this tweak you can set one of those included by to the developer. Quantum has a settings menu available in the Settings application of iOS, and there you can choose one of the fonts available for you, but don't imagine that you will have an extremely large selection. After choosing the font, press Respring and the new notifications will be displayed with that font.
Quantum is available in Cydia's ModMyi repo.
