The recent announcement that Red Hat will acquire JBoss will have some interesting effects in the open-source application server domain.
Several years ago when Red Hat started to charge for its Linux distribution by-way-of the Red Hat Network, the justification was that the for-cost Red Hat Enterprise Linux (RHEL) distribution was guaranteed to be fully integrated, tested and stable for longer periods of time than the spin-off open-source (free) Fedora distribution. See the official Red Hat comparison below: