It worked fine in 2.5 and 2.4.4

Python 2.5.1 (r251:54863, Jun  2 2007, 19:09:15) 
Type "copyright", "credits" or "license" for more information.

In [1]: from cStringIO import StringIO

In [2]: from array import array

In [3]: a = array('B', [0,1,2])

In [4]: StringIO(a)
---------------------------------------------------------------------------
<type 'exceptions.TypeError'>             Traceback (most recent call last)

/Users/reedobrien/<ipython console> in <module>()

<type 'exceptions.TypeError'>: expected a character buffer object


Recompiling with the 2.5 cStringIO.c it works.

Python 2.5.1 (r251:54863, Jun  2 2007, 20:06:12) 
Type "copyright", "credits" or "license" for more information.

In [1]: from array import array

In [2]: from cStringIO import StringIO

In [3]: a = array('B', [0,1,2])

In [4]: StringIO(a)
Out[4]: <cStringIO.StringI object at 0xe8c0>



I blame Visual Studio. 
I don't know enough c to fix it.