I think it's about time that "well-maintained" and "supported" stop being used as some kind of differentiating point against Linux. There are just as many, if not more, regular updates, both in terms of packages and new distribution releases, to the popular Linux distributions as there are for OSX and Windows. This is even more impressive when you take into account that any random Linux distribution comes with more software out of the box than either OSX or Windows. Both Ubuntu and Redhat provide significant lead time on their release schedules and give you access to the next release before it is official, allowing you to plan your upgrade path better. Even when a distribution is EOLed, you can find people who still offer packages and upgrades for it, and to top it off you can maintain your own upgrades if the vendor EOLs a release and your environment requires not upgrading. Linux distribution releases are not as marketing based as OSX or Windows releases and release schedules, and you don't need to wait until the official day, or be some kind of partner, to find out what's going to be in the newer versions before it is released.