Depends on the distro. Most mainstream distros have horribly out-of-date software (by choice). There are distros that do keep near-bleeding edge software in their repos, Arch Linux is one such distro, I've seen packages appear for new releases within a few days, at worst I've seen a package only a few revisions behind.
Can someone tell me how AD is licensed?
Afiak it is just a subsystem of Windows Server thus requires no additional licenses. But there is some bizarre ass license subsystem (of Windows Server) that the summary refers to. I'd suggest reading the ToS.
IANA Windows SA.
Why is Slashdot so biased towards open source?
Becase many nerds have a 'hacker' mentality, where if they purchased a physical device they own it and can do anything they want with it, DRM, DMCA, vendor-lock-in and other such evils are viewed as evil because they inhibit hacking.