Poison says at the beginning of your turn, so does this mean to use Poison you must use it where you are standing, and that you cannot move, and then use poison in the same turn?

Right. yep

Rep for you, thanks!

That said, you can Outwit a defensive power and then Poison as Outwit, as a free action, can be used during the "beginning of the turn" phase and since it's still that phase, Poison kicks in.

Or just slap Armor Piercing on your Poisoner.

Ok, so to clarify (I already know these answers I'm just trying to find a way to appropriately explain 'beginning of the turn') the beginning is before any actions other than free actions are taken?

Good question. Any power/move actions, certainly put you out of the beginning of your turn. But in terms of outwit, you can outwit someone before you poison them that very same turn, because free actions at the beginning of your turn can be done in any order.

Not necessarily.
Not true.
It has nothing to with being free or non-free.

You are no longer at the beginning of your turn once you have given an action which does not say "at the beginning of your turn" or "at any time during your turn" or something similar.

I can give an agent of Oracle a power action to turn the dial to Outwit, then use that Outwit to remove some Impervious, then Poison the guy. I'd still be in the beginning of turn.

To build on what Harpua said - I can use Nanobots, which is a free action and then I would NOT be in the beginning of my turn any more.