A new SFS2X update is available with new powerful features and fixes discussed in the support forums recently:

• Improved scalability and thread management via Auto-scaling Thread Pools. No more need to fine tune threads by hand
• BlueBox v3.0: revamped and improved edition running on the latest Jetty 9
• Integrated file uploads
• Added support for websockets over SSL (WSS)
• AdminTool: Extension Manager module, allows to manage, upload and deploy Extensions directly from the Admin GUI
• AdminTool: administrators can now be given access to a selection of modules and server halt/restart permissions

… lots more …

You can read the full release notes and download the installer from here.
Also check the latest HTML5 client API supporting the WSS protocol and the porting of the SpaceWar game to Unity (available in the Unity examples package).