There is already an unreasonably high number of threads on this, but to sum it up, here's what it means. A DMCA takedown means the files cannot be distributed legally. This is why we cannot download it now. The reason the DMCA was issued has to do with licenses and copyrights. I'm not going to go into details or speculate beyond that because there are enough threads like that on the forums already. All anyone needs to know is that if you want to start a CraftBukkit server right now, then you either have to already have a copy of the CraftBukkit jar file in your possession or you might be able to get one from a server host that had one before the takedown. If neither of those options work for you, then I'm sorry for your bad luck. You tried to start a server at a bad time.
My Opinion: One of the retired staff copyrighted a lot of the bukkit code, when he left the bukkit team because of the eula he put a DMCA takedown on the bukkit code. Bukkit have to replace it or remove the project.
You might not have a definite answer to this question but will craftbukkit ever be able to be downloaded again? And if not does that mean there will be no more playable servers after Minecraft updates?
===RhysyB=== Nobody has a definite answer. And minecraft has its own servers and there will always be somebody wanting to make server side modifications ( what we are doing with plugins ) so there will always be somebody developing something.
timtower Great To Know That We Will All Still Be Playing Minecraft; Appears I Have Started A Server At The Wrong Time