u\xa0 should be a white space:
== python 2.7.3 ==
Python 2.7.3 (default, Aug 1 2012, 05:14:39)
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> fn=u'\xa0'
>>> print fn
>>>
== IronPython 2.7.3 ==
IronPython 2.7.3 (2.7.0.40) on .NET 4.0.30319.269 (32-bit)
Type "help", "copyright", "credits" or "license" for more information.
>>> fn=u'\xa0'
>>> print fn
?
>>>
it was translated to a '?' in ironpython