interleave string

[Andrea Crotti]

Just a curiosity not a real problem, I want to pass from a string like

xxaabbddee
to
xx:aa:bb:dd:ee

so every two characters insert a ":".
At the moment I have this ugly inliner
        interleaved = ':'.join(orig[x:x+2] for x in range(0, len(orig), 2))

but also something like this would work
[''.join((x,y)) for x, y in zip(orig[0::2], orig[1::2])]

any other ideas?