It turns out that this is related to having two different versions of codesign_allocate . To fix the problem, do the following in a terminal window.
sudo ln -s /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/codesign_allocate /usr/bin
After that you can share the IPA with organizer again.
You can also package from the Terminal window with the following commands in the directory containing your XCode project.
xcodebuild -target LocateCustomer -sdk iphoneos build
/usr/bin/codesign -f -vv -s "Divya Mahajan (5E58XNSTHR)" build/Release-iphoneos/LocateCustomer.app
xcrun -sdk iphoneos PackageApplication -v "build/Release-iphoneos/LocateCustomer.app" -o build/LocateCustomer.ipa --sign "iPhone Developer: K Developer (5E68XNSTHR)"
--- Here LocateCustomer = Target name in the project.
