You need to do the following in order to install ikiwiki in ubuntu 8.04:
sudo apt-get install ikiwiki sudo perl -MCPAN -e 'install XML::SAX' sudo perl -MCPAN -e 'install XML::Simple' sudo perl -MCPAN -e 'install HTML::Scrubber'
sudo perl -MCPAN -e 'install Text::Textile'
Done!