They can not say it but Linux distribution Centos is build from RPM source from one of the major Linux distrobution. Red Hat. You can find the link where we can locate the link to Red Hat.

http://www.centos.org/modules/tinycontent/index.php?id=2

Under General Public License and others open source licenses related to Linux and open source application. This is not a problem. Other than removing any copyright or IP of the Red Hat. The others software and Linux can be distribute again.

Refer this link http://www.opensource.org/

Red Hat should be like it because it such a promotion when system admin that used Centos when they have the budjet and want a stable company to support them. The migration should be easy.