There is a new freeCydia tweak available for the iPhone and iPad that adds brightness icons to your springboard. Tapping these Brightness Icons will raise or lower the brightness without accessing your settings or App switcher. Holding down on either of these will result in either the maximum or minimum brightness. This Cydia tweak does require that Winterboard be installed on your jailbroken iPad or iPhone.
To move these icons, you'll need to tap and hold on a different icon since the long press on these icons has a different feature enabled. What do you think?