Chpwn just announced that a new tweak, made in collaboration with p0sixninja, called Gridlock will hit Cydia store soon. From what we can tell, this tweak lets you position the icons on your SpringBoard in any way you want to, breaking the rows and columns restriction. It will ( probably ) be available for iPhone/iPod Touch/iPad and it will cost $1.
We will keep you up to date. Stay tuned…