OMG I forgot the return statement...

foo.py

#!/usr/bin/env python

def baz(f):
    def wrapper(*args, **kwargs):
        print 'Calling wrapper...'
        return f(*args, **kwargs)
    return wrapper

class Foo(object):
    def __init__(self, i):
        self._i = i

    @property
    @baz
    def i(self):
        return self._i


if __name__ == '__main__':
    f = Foo(100)
    print f.i