You Can Charge a MacBook with a MacBook Pro Adapter
For those wondering if you can charge a MacBook with a MacBook Pro power adapter - you can. The MacBook Pro power adapter has two modes, one for 18.5V @ 4.6A (85W) and another for 16.5V @ 3.65A (60W). It automatically senses what it's plugged into and if it's plugged in a MacBook it uses the 16.5V setting. I learned of this when my MacBook started running out of juice whilst working on homework at the College of Computing as Justin was sitting next to me with his MacBook Pro & adapter.
We looked at the label on his adapter for a while, debated for a while, then I backed up my really vital stuff and plugged his adapter in. No problems at all. As for the other way around, you can use a MacBook power adapter with a MacBook Pro but it will charge very slowly.