You might find the WebHelpers html_quote function useful:
http://pylonshq.com/project/pylonshq/browser/WebHelpers/trunk/webhelpers/util.py

Specifically asciification:

if not isinstance(s, basestring):
     if hasattr(s, '__unicode__'):
         s = unicode(s)
     else:
         s = str(s)
s = cgi.escape(s, True)
if isinstance(s, unicode):
     s = s.encode('ascii', 'xmlcharrefreplace')


--
Ian Bicking  /  ianb@colorstudy.com  /  http://blog.ianbicking.org