Recently bukkit has been issued a DMCA takedown because of recent events and the massage below appeared on bukkit’s downloads pages.

451 Unavailable for Legal Reasons.
This content is unavailable as the direct result of a DMCA takedown request.
A copy of the notification can be found at this link.

What now?
well, we don’t know, as far as we are aware Wesley Wolfie is issuing the DMCA notice to Multiplay (who host bukkit and bukkit’s download links (reference)).

I believe that Spigot will continue to update there builds but are in the same boat as bukkit, but that it is ok for them to do so as it is not Wolfie’s Intention to stop the modding of bukkit but to protect mojang from using his code in their develpments of bukkit as he was unaware that mojang had aqquired bukkit and he was no longer working for an open source project and was now working for mojang essentially for free.

To read more, read here!