Q: Mid-2012 MacBook Pro RAM compatible with 2009/10 MacBook?

I just upgraded the RAM in my mid-2012 MacBook Pro from 4 GB to 8 GB and I have a friend with a 2009/10 MacBook with 2 GB. This article http://support.apple.com/kb/HT1651#link1 seems to indicate that that model of MacBook's recommended RAM is DDR3 1066 MHz. The 2 GB memory modules left over from my MBP are DDR3 1600 MHz. Could my friend use those or not?