I wanted to upgrade my RC but according to the "UPGRADING" file included in RC the procedure to use depends on the version you're presently using.
How do you know which version you are using?

Eric, there is a version string in the config file main.inc.php in the roundcube config dir:

// add this user-agent to message headers when sending
$rcmail_config['useragent'] = 'RoundCube Webmail/0.1-rc1';