Verify this:

[g@eq]~/i/code/trunk/server/memcached/src/main/resources% python sample_python_memcached_writer.py
Testing set ['Simple_Key': Simple value] ... OK
Testing set ['Expiring_Key' : 999 : 3] ... OK
Testing increment 3 times ['Incr_Key' : starting at 1 ] ... OK
FAIL: returned 50
FAIL: returned 51
FAIL: returned 52
Testing decrement 1 time ['Decr_Key' : starting at 4 ] ... OK
FAIL: returned 51
Testing decrement 2 times in one call ['Multi_Decr_Key' : 3 ] ... OK
FAIL: returned 50

It appears that the returned values are ASCIIs rather than numbers itself.