I think we really should all do our best to shop at Overstock with BTC as soon as they accept it so they see it was a good idea and then other retailers will follow suit.
edit: has Overstock said what they will do with the BTC? Will they sell it on an exchange?
I don't think they have announced what they will be doing with the Bitcoin. I'm assuming they will be exchanging it or if they want to try and be smart they will try and sell at a higher price.
They already said they will be using derivatives to hedge against changes in bitcoin prices.