Placing a torch on the ground or on the side of a block then breaking the torch while looking at the block it is on will break the block it is on. spawners are included in this. I'm on a vanilla server and this has happened to myself and others on the server. The server does have bukkit on it as well for admen to use and for the other worlds on the server that are allowed warps.

When the block breaks it will only drop the block item if that block is breakable with a fist only. (IE: cobble and smooth stone just vanish, while sand will drop a sand block)