Do you mean the cord that plugs into the wall outlet? If so yeah, that can be done. But the other half is completely incompatible with the iPad.
I know this is old but I wanted to bump the thread to make sure this still held true for the new iPads 10W charger? I want to take the wall adapter for my 85W MBP and connect it to the 10W USB wall charger that came with my device. Is there any apple support docs that confirm this wont harm the device? Am I better off just buying this?: http://store.apple.com/us/product/MC359LL/A?fnode=MTc0MjU4NjA