Bulletin Pro is a cydia tweak that allows you to change notification center and banner position and size.

The things you change are:
Change Animation of the Banners
Change Position of the Notification Center
Change Size of Notification Center
Change the Size of the Banner
Modify Notification Center and Banners
Disable StatusBar Double Height
You can download Bulletin Pro via the BigBoss Repo for $0.99 or get it free from the iGoldhouse repo