There is a robot that executes very small trades apparently to astroturf the mtgox last trade price. My question is why would someone spend perfectly good money to do that?
A lot of merchants set their exchange rate based on the current best bid at Mt. Gox bid, or on Mt. Gox last. So if you are buying something of a larger value from a merchant that uses best bid as the rate, then it usually is worth the money to narrow the spread a little. You can trade a few pennies on Mt. Gox and as a result maybe save a few dollars (or a lot more) by getting a better price quote from the merchant.
Coinbase is one such bitcoin seller that uses best bid.
I was thinking there would be a service by now that one could pay and it would attempt to raise the best bid. Maybe someone has done this and that's what you are seeing.
