The proposal is to add a .hex method (similar to binascii.hexlify) that is the inverse of .fromhex (similar to binascii.unhexlify), as originally specified in PEP 358.
http://legacy.python.org/dev/peps/pep-0358/
"The object has a .hex() method that does the reverse [of .frombytes]
   >> bytes([92, 83, 80, 255]).hex()
   '5c5350ff'
"
If we add .hex, I think we should stick with this: no 0x or \x prefix. 

To aid debugging, I would change spaces to be None or a positive int n to insert a space every n bytes.  So .hex(8) for an array of 64 bit ints.