Build failures in XCode 3.2.2 when copying plists for iPhone development

I created a plist file and when I built my project I received the following error:

CopyPlistFile build/Debug-iphonesimulator/ TestArray.plist
cd /Users/arockwell/dev/TestApp
 setenv PATH "/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Developer/usr/bin"
/Developer/Library/Xcode/Plug-ins/CoreBuildTasks.xcplugin/Contents/Resources/copyplist --convert binary1 TestArray.plist --outdir /Users/arockwell/dev/DrinkMixer/build/Debug-iphonesimulator/
sh: plutil: command not found
Command /Developer/Library/Xcode/Plug-ins/CoreBuildTasks.xcplugin/Contents/Resources/copyplist failed with exit code 127

Google turned up no helpful information about the source of the problem. The most obvious workaround I could think of was to simply make a symlink in /Developer/usr/bin to /usr/bin/plutil.

ln -s /usr/bin/plutil /Developer/usr/bin/

I wish I understood the root cause of the problem, but that seemed to do the trick.