I'm running TWiki without the ".pl" extension. I have several TWiki 3 ("Cairo") installations and I'll upgrade them to TWiki 4 "eventually". Here's my guide to installing TWiki 3 if anyone is still interested: http://g-b.dk/bin/view/Main/InstallTwikiOnDreamhost
Note: The installation guide for TWiki 3 does not competely apply to TWiki 4 because there have been improvements in the configuration, but some parts are still useful.
I have also made some test installations of TWiki 4 on DH, and that also worked without the ".pl" extension, see http://wiki.g-b.dk/ (subject to change). I haven't written a similar installation guide for TWiki 4 yet, though I will do that "eventually" too.
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