Some Experience (Score 2)

I feel like I can speak to this with some authority...
Generally, the reason any company uses OEL is because they're running DBMS (and related products) and they've been convinced/intimidated by an Oracle rep that there will support compatibilities with any other combination (generally in the form of "Oracle will just blame any performance issues on the OS") which is ironic given the RHEL "binary-compatibility"... and/or more importantly, they've been informed there will be "trouble" with their licensing if they use anything else... "Shame if we had to come in here and audit you and declare you have to license every CPU in your data center because you're running Oracle on an unauthorized hypervisor..."

The meat of this announcement, such as it was, was that they REALLY want more ISVs to directly certify their products on OEL so they can be a part of that whole ecosystem more. It is where Red Hat really has a core strength right now (and probably core profits) and definitely where Oracle will be hurt post-9.2 if that continues.