I saw no problems in theory either. In practice, I have thus far been unable to succeed.
Using default repos, for both 64bit CentOS and 64bit RHEL, "yum search openjdk" produces only .x86_64 results. Instead of .x86_64, I am interested in laying down the 32bit version of OpenJDK on the 64bit OS .i586,.i686 or whatever it might be. Explicity searching for the same package name but using i586/i686/etc does not turn up any installable packages :-/