The Mt. Gox streaming API has a market depth channel. What is the "price" value given in that channel, and what does it represent?
It's the price per BTC for the specified order. The "type_str" field specifies the type of order ("ask" or "bid"), the currency specifies the currency in which the price is quoted.
The example listed refers to an "ask" order of 14.43 USD/BTC.