Mojang's Notch is a smart person, not only in game design terms but also when it comes to managing the company's 20 million or so Minecraft players. The designer posted on his blog a poll to determine if his cuboid friends would be comfortable with the company's decision to collect anonymous data from their users.
Mojang currently tracks only when a player logs in to the game. Notch proposes to track "non-private" information such as the duration of the game session and OS type, as well as 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 shared with the community, "as usual."
"Naturally the information you send will be completely anonymous," said Notch. "So it wouldn't contain any session information or your user name, and it doesn't provide any sensitive information you might not want to disclose." Minecraft crafting shocked that this type of data isn't being collected in the first place, but we'll admit it. If you're part of the Minecraft nation you can make your voice heard by voting in favor or against data collection that is anonymous here.