We could really use some statistics on coinbase, such as volume and historical pricing. I think there's a chance they might have huge volume. They started off tracking the MtGox exchange rate, then it was inline with Bitstamp, and now it is somewhere in between. I bet they have high enough volume both buying and selling that they can discover the price internally pretty well without having to exchange too much with Bitstamp or MtGox (which they probably don't do at all).
I don't think they want us to know the statistics on coinbase. They don't want it to be used for 'trading' but for actual 'exchange'.
I second this opinion, they don't want to turn out like mtgox or anything. They just want to bring a suitable, easy to use exchange for people more casually using the currency.
