I used the following script to symbolize the crash report I got from the user:
/Developer/Platforms/iPhoneOS.platform/Developer/Library/Xcode/Plug-ins
There is a known issue in the symbolicatecrash utility that ships with iPhone SDK 2.2.1 also, if that's the SDK you're currently using. You need to download the new binary from http://developer.apple.com/iphone/library/technotes/tn2008/tn2151.html
Hope this helps your troubles.