Keep in mind this thread was made just after the iPad was announced. It hadn't even shipped yet so no one could have tried it out yet except for the people at the keynote.
Every 6 months you'll need to put ONLY ONE drop of machine oil inside that hole. It will keep your iPad in good shape, all moving parts working without friction.
Whatever you do, don't stick a pin inside that hole!!!
WARNING: The above was a joke (I don't want any poor fellow to fall for it and damage the microphone).