Bukkit/CraftBukkit — pull request #927 by zerg960 (2012-11-15 23:39:31+00:00)
Title: Add API for Client Difficulty & Render Distance

This adds an API to retrieve the client's difficulty setting & render distance set in their options.

Currently, it is impossible for plugins to retrieve that data, although it is sent by the client.

There's also a pull request to update Bukkit, somewhere.