Mojang's Notch is a smart guy not just in terms of game design, but also in the management of the company's 20 million or so Minecraft players. The designer has published a poll on his personal blog to determine the opinions of his cuboid players. be comfortable with the company collecting various kinds of anonymous data from its players.
Mojang currently tracks only when a player logs in to the game. Notch proposes to collect "non-private" data, like the length of a gameplay session, OS type, whether you are playing in single or multi-player mode, and whether you are using the client or the web applet. The collected information would then be made available to the community, "as usual."
Notch stated that the data will be sent "naturally" anonymously. It wouldn't contain the details of your session or user name, and it will not transmit any sensitive information that you wouldn't want to share. We're a bit amazed that this kind of data isn't being collected, to be honest. You can vote here to support anonymous data collection or against it for those who are part of the Minecraft nation.