http://code.google.com/p/gsutil/issues/detail?id=71

--- a/gsutil
+++ b/gsutil
@@ -41,13 +41,15 @@
   _OutputAndExit('Unable to determine where gsutil is installed. Sorry, '
                 'cannot run correctly without this.\n')
 boto_lib_dir = os.path.join(gsutil_bin_dir, 'boto')
-if not os.path.isdir(boto_lib_dir):
+if os.path.isdir(boto_lib_dir):
+  sys.path.insert(0, boto_lib_dir)
+try:
+  import boto
+except:
   _OutputAndExit('There is no boto library under the gsutil install directory '
                 '(%s).\nThe gsutil command cannot work properly when installed '
                 'this way.\nPlease re-install gsutil per the installation '
                 'instructions.' % gsutil_bin_dir)
-sys.path.insert(0, boto_lib_dir)
-import boto
 from boto.exception import BotoClientError
 from boto.exception import InvalidAclError
 from boto.exception import InvalidUriError