After comparing Twisted and Medusa, I have concluded that I prefer Medusa over Twisted.  My reasoning is that extra functionalities and flexibilities have little value if they are difficult to access.  Twisted is hard to grok.

At this point, I am looking for an equivalent of Lucene for Python.  I know that Lucene has been ported to .NET (NLucene), but I am not aware of a Python port.  Some have suggested sgrep.  If you have a recommendation, please let me know.  As this list of search engines show, there are too many to consider and little time to do it.