Is it possible to have any missing pages(404's) redirected to the search(omega) ?
So if someone comes to my site with http://example.com/foo_was_here it would result in 'foo_was_here' being passed as a search parameter to omega ? --Mick

DONE

I use nginx instead of apache.
Just add the following to the server block outside of any location block in nginx.conf
You must also make sure you have setup and enabled the search plugin(omega)

error_page  404              /ikiwiki.cgi?P=$uri;

My full nginx.conf

server {
        listen  [::]:80; #IPv6 capable
        server_name  www.lunix.com.au;
        access_log  /var/log/nginx/www.lunix.com.au-access.log  main;
        error_log  /var/log/nginx/www.lunix.com.au-error.log warn;
        error_page  404              /ikiwiki.cgi?P=$uri;

location / {
                root    /home/lunix/public_html/lunix;
                index  index.html index.htm;
}

location ~ ikiwiki\.cgi$ {
                root    /home/lunix/public_html/lunix;
                include /etc/nginx/fastcgi_params.cgi;

                fastcgi_pass   127.0.0.1:9999;
                fastcgi_param  SCRIPT_FILENAME  /home/lunix/public_html/lunix$fastcgi_script_name;  # same path as above
        }
}