This number doesn't really have that much significance. Obviously every bitcoin user is going to rush and make an order the first day to test out the system (or inflate the numbers). But what does it say about sales over a whole year? Or how many new users it'll attract?
When your margins are as low as they need to be in order to compete in this market, adding something like an option for Bitcoin payments, which is paid for by the customer during checkout (processor fee), is a no-brainer.
I do not have an account at overstock. I never planned on having an account at overstock, nor did I plan on ever making a purchase on overstock. Yet, I am now a potential new customer thanks to the fact that they've added an option for Bitcoin payments.
You can argue that attracting bitcoiners is like tossing a pebble into the sea, but when there is no drawback in doing so, it only makes sense. You might consider how quickly the bitcoin user base is growing as well. These are long term plans.
