The basic gist of it is, "We're developing this for ourselves, you can use it under our terms, but don't come crying if it causes a nuclear meltdown."
Companies can use it for proprietary reasons, but they have to include the licence in documentation.. quite a few proprietary companies stay around, or hire someone to monitor the situation, typically they'll contribute back.. but it's not a requirement.
http://www.daemonforums.org/showpost...4&postcount=27