After using iPhoto '09 for a couple days, I have come to love the new features, in particular the Places feature. However, one thing that annoyed me is that you cannot use the Multi-Touch feature on newer MacBooks to manipulate the maps (zooming in/out, etc.).
However, thanks to a Tweet-tip from Steven Troughton-Smith (@stroughtonsmith), there is a way to enable this functionality. To add Multi-Touch maps to places in iPhoto '09, just open Terminal.app (/Applications/Utilities) and type (or copy/paste) the following statement and press enter:
defaults write com.apple.iphoto MapScrollWheel -bool YES
When you restart iPhoto, you will notice that you are now able to scroll in/out of the Places maps with ease. If it turns out that you don't want the scrolling feature, just retype the statement, replacing "YES" with "NO."
Thanks for the tip, Steven!