Update: 13w18b was released to fix some crashes.
Changelogs:
To get the snapshot, use the new launcher available in the link below. To return to 1.5.2, simply start the old launcher and play as normal.
Windows: Server 1 Download – Server 2 Download
MAC/OSX: Server 1 Download – Server 2 Download
Linux: Server 1 Download – Server 2 Download
Server files:
Cross-platform jar: http://s3.amazonaws.com/Minecraft.Download/versions/13w18b/minecraft_server.13w18b.jar
Windows EXE: http://s3.amazonaws.com/Minecraft.Download/versions/13w18b/minecraft_server.13w18b.exe