This plugin permit to use "@a"; "@p"; "@r" on the chat, and on the console.
We can notice "@p" represents the closest player, so yourself; "@a" represents all of the players online; "@r" represents a random player. Finally, "@c" represents the closest player to you, and that node was added due to the request of somebody [Since SBC 1.1]
This plugin was released because CraftBukkit don't consider "@p"; "@a"; "@r" when using them in the chat or in the console, whereas MinecraftServer consider them. It is also convenient when the server don't use the plugin Essentials, especially for teleport all players to yourself, or reset the scoreboards.
All of the versions of SilverBlockCommand are compatibles with every builds of CraftBukkit since the 1.1-R1.0 [Implementation of the new event system].