Beware, that Joomla RC3 does not work properly with "older" PHP Versions like 4.3.11. I had to go back to RC2. Some of the generated links will no longer work, like "Popular" or "Polls".

Meanwhile I found a way to use php5 on my hosters machine. All I had to do is enhance the ".htaccess" file with the following lines:

########## Begin - Switch to PHP 5.2
Action php /cgi-php52/php
AddHandler php52 .php
########## End - Switch to PHP 5.2

########## Begin - Switch to PHP 5.0
# Action php /cgi-php5/php
# AddHandler php5 .php
########## End - Switch to PHP 5.0