I realized that some people may be interested in a quick recap of what's happened to all the Java-based server implementations that were announced since the DMCA about 7 months ago. Here goes.
- CraftBukkit: Totally dead
- Spigot: Alive and suitable for production, has builds available without Spigot optimizations for those who prefer something more vanilla-like
- Sponge: Released working alpha for the Forge version yesterday, vanilla-based version still in development
- Granite: Merged into Sponge as a base for the vanilla version, still in-progress
- Project Rainbow: Still alive, with small community producing plugins
- Husk: Total vaporware