It’s called Flow Free and is available here http://itunes.apple.com/app/flow-free/id526641427?mt=8
It’s made by Big Duck Games, and grats to them for hitting the top of the iPad free list!
You basically have to connect colored dots, circuit-board fashion, without touching each others’ ‘pipes.’
A bit of tron lightcycles is in the mechanic, but without the timed aspect, which makes the greatest thing is the pacing.
Check it if you have an iPhone or iPad!
(The iPad version has bigger grids, which get scarily hard.)