2004-10-04 : If Howling Mine leaves the battlefield before it resolves, then the last known tap or untap state of the card is used for resolution.

2004-10-04 : It does not trigger at all if this is tapped at the start of the draw step, and it checks this again on resolution.

2004-10-04 : The additional draw is separate from any other draw during your draw step. It happens when the triggered ability resolves.

2013-04-15 : The triggered ability is put onto the stack after you have already drawn your card for the turn.