Gould: Oracle to Red Hat: It's Not Your Father's Linux Market Anymore

By that definition of proprietary - I actually think you mean commercial - it would be a better word I think. Red hat has NO lock-in effect - seeing as you can swap RedHat with CentOS and have the exact same features/patches.

This is why I know some customers who use CentOS for their FC attached servers (to communicate with a SAN) - since CentOS's multipath version actually works properly (I tested Ubuntu's LTS 8.04 - it fails miserably).