Craftbukkit was never licensable under the LGPL. From the projects inception, it contained proprietary, closed-source Mojang code used without a license. It's LGPL license was invalid from the start.
From the get go we were plagued with issues and obstacles we needed to overcome, one of which we were sadly unable to tackle despite our best efforts: the legal barrier of licensing and permission. When starting the Bukkit project and even getting involved with hMod before that, we all knew that our work - no matter how well-intentioned - fell into a dangerous legal grey area. - EvilSeph[1]
This calls into question the legal standing of all derivative works of Craftbukkit.
The contributors still have copyright over the things they wrote, but they also weren't writing them in a vacuum. They were creating derivatives of Craftbukkit under the assumption it was valid LGPL.
The LGPL wasn't violated because it came out that Mojang controls the Bukkit project. It was voided before these contributions came into question. It's not clear what license, if any, the contributions by Wesley, et. al. fall under.
I am very interested in the legal issues of this whole situation and am constantly looking for the best resources I can find. If you're curious, I suggest reading some posts by /u/VideoGameAttorney on reddit[2]
[1] https://forums.bukkit.org/threads/bukkit-its-time-to-say.305...
[2] http://www.reddit.com/user/VideoGameAttorney