...or more specifically development and bug testing.
Yes, RedHat did it first with the Fedora Project and that endeavor is moving along quite well. Remember how we all bemoaned the loss of RedHat Linux? And, in the beginning there was much concern over FC's stability but IMHO everything is working out just fine. FC gives you bleeding-edge technology and is pretty stable, at least in my experience. It is amazingly fast (especially with my old GeForce4 card when tainting the kernel with the nVIDIA drivers ;-). I currently use Fedora Core 3 with packages from FreshRPMS and others for desktop and multi-media applications. It works great! If you need an enterprise GNU/Linux solution along the lines of RHEL but don't need a support contract, CentOS builds a fine distribution.
At any rate, RedHat took a bold step in the Fedora Project initiative and I think they deserve a lot of credit for it, especially for all the heat they took over it.
Novell/SuSE has obviously seen the advantages of the this approach and is reaching out to the community in opening up SuSE Linux to outside contributors. This is a huge step, but not unproven. I think it was a very wise decision which will benefit both the company and the community. Thanks SuSE!