>>> "Universe.World.Country.State.City.Street".rsplit('.',1)[1]
'Street'
Edit: rpartition as suggested by SilentGhost seems to be the most efficient
# rpartition
$ python -m timeit -r100 -n100 -s 'x="Universe.World.Country.State.City.Street"' 'x.rpartition(".")[-1]'
100 loops, best of 100: 0.749 usec per loop
# rfind
$ python -m timeit -r100 -n100 -s 'x="Universe.World.Country.State.City.Street"' 'x[x.rfind(".")+1:]'
100 loops, best of 100: 0.808 usec per loop
# rsplit
$ python -m timeit -r100 -n100 -s 'x="Universe.World.Country.State.City.Street"' 'x.rsplit(".",1)[1]'
100 loops, best of 100: 0.858 usec per loop
# split
$ python -m timeit -r100 -n100 -s 'x="Universe.World.Country.State.City.Street"' 'x.split(".")[-1]'
100 loops, best of 100: 1.26 usec per loop
# regex
$ python -m timeit -r100 -n100 -s 'import re;rex=re.compile(r"\.([^.]*)$");x="Universe.World.Country.State.City.Street"' 'rex.search(x).groups()[0]'
100 loops, best of 100: 3.16 usec per loop