MacWorld's MacBook FAQ (syndicated to Yahoo! News) answers one of my questions from the other day, as follows:

I already own a MacBook Pro—can I use the power supply that came with it on a MacBook?

If you hold the two power supplies side by side, you’ll notice that the MacBook Pro’s is larger. That’s because the MacBook Pro uses an 85-watt power supply, while the MacBook uses a 60-watt power supply. Apple says you can use the more powerful, 85-watt power supply with a MacBook without any problems, and that in 80 percent to 90 percent of situations, you can use the MacBook’s power supply with the more-demanding MacBook Pro as well. If you’re really taxing the MacBook Pro’s processor with some heavy-duty work, the MacBook’s adapter will still be able to power the MacBook Pro—but it may not have any power left over to charge its battery.