try deepend instead of 3dboard first, its free, however they're not scrolling wallpapers as such, they just move the wallpaper slightly like ios 7. the description for multiwall says it allows panoramic wallpapers, haven't tried it myself though
This isn't a scrolling wallpaper tweak, but its a neat option. The tweak I'm referring to is Pages+. It allows you to use a wallpaper on each page of your springboard. I bet it would be pretty cool paired with Deepend.
Anyways, since we're talking about wallpaper tweaks, just thought I should throw this out there.
Hopefully someone comes out with a tweak to replicate iOS 7 scrolling panaramas that uses motion instead of my fingers. Thats the eye candy I was hoping for from iOS 7!