% python
Python 2.3.3 (#1, Feb 12 2004, 08:44:01)
[GCC 2.95.4 20011002 (Debian prerelease)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import quixote
>>> quixote.__version__
'0.6.1'
>>> t = 'hi'
>>> t += quixote.html.htmltext('there')
>>> t


% python
Python 2.2.1 (#2, May 28 2002, 10:43:30)
[GCC 2.95.2 19991024 (release)] on sunos5
Type "help", "copyright", "credits" or "license" for more information.
>>> import quixote
>>> quixote.__version__
'0.6.1'
>>> t = 'hi'
>>> t += quixote.html.htmltext('there')
Traceback (most recent call last):
  File "", line 1, in ?
TypeError: cannot concatenate 'str' and 'htmltext' objects
>>>

... so it's either a SunOS / Linux thing, or, more likely, an older-python
thing.  Things have changed in how python does inplace operators, but I
don't know exactly when.  Can anyone else out there with an older python
verify this?