Hmm that sounds strange. Do you have /tmp/wiki created at all (it should be done automaticly). If yes - try entering http://localhost:8080/wiki/Main ... it shall show empty Main page... you sould be able to edit it...
if no - can you paste your deploy log from deploying wiki portlet ?
I have the same problem
Have you tried beta release ?
Alpha was very buggy.
I am receiving many deploy errors when trying to install [Binary Beta Version -- Wiki 10/31/05] under JBOSS 4.0.4 OS: WIN2000.
I copied wiki.ear to ..\server\deploy\wiki.ear
Pleae give me instructions on how to proceed.