As I'm sure you know, Mojang has just put out a new version of the client (1.6.4). Bukkit, however, has not been updated yet, so you'll need to use the previous version (1.6.2) to log onto Graalians Minecraft and most other servers.

If you've already upgraded, don't fret! Downgrading your client is now easier than ever thanks to the new Minecraft Launcher. Click here for a helpful guide I found.

Graalians Minecraft is currently running on 1.7.4 which is the latest Bukkit release.