Well there is no upgrade path from beta/rc however there is no functional difference between beta/rc/final
Thus, as always, if you installed from the beta/rc and it is working just leave it alone. The only difference between beta/rc/full is the versions that are on the actual ISO. the full release was updated to whatever is current from the CentOS repo as of 2300 EDT yesterday. Also the date in the initial boot up screen was changed to reflect yesterday.
We try not to change the ISO at all as it only has 2 PIAF created programs on it. The real magic is in the payload files which are never part of the ISO's These files contain the latest and greatest asterisk improvements for NEW installs.
I am still working on update-source to make it CentOS5.6ized not done yet. If Centos would stop putting out kernels that need to be massaged to run all of our stuff it would make things go faster.
Tom